HomeMy WebLinkAboutAPA3344IS
FACTORS INFLUENCING BEHAVIOR AND
SIGHT ABILITY OF MOOSE IN
DENALINATIONALPARK,ALASKA
QL
737
.U512
L56
1982
A
Thesis
Master of Science
By
Carol Linkswiler
University of Alaska
Fairbanks, Alaska
May 1982
(
FACTORS INFLUENCING BEHAVIOR AND SIGHTABILITY OF MOOSE
IN DENALI NATIONAL PARK, ALASKA
RECOMMENDED:
APPROVED:
.z..,k.. jl (! ~
~c~
Director,
1
Vice Chancellor for Research and Advanced Study
Date
Fisheries
· {_)L·-t·s ./~~.~.{. ~ ....
Alaska Resources
Lihrary & lnfürrnatwn Servtces
,:\nchorage, Alaska
.~CSUUl.'-''1;;;~ 11. ....
egional Office
Park Service
FACTORS INFLUENCING BEHAVIOR AND SIGHTABILITY OF MOOSE
IN DENALI NATIONAL PARK, ALASKA
A
THESIS
Presented to the Faculty of the University of Alaska
in Partial Fulfillment of the Requirements
for the Degree of
MASTER OF SCIENCE
By
Carol Linkswiler, B.A.
Fairbanks, Alaska
May 1982
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ABSTRACT
Moose in Denali National Park were studied in 1976-77 to assess
aspects of moose behavior that might influence their sightability
during aerial surveys. Interrelationships among diurnal activity,
habitat use, and aggregation patterns were considered, and the
relationship of season and weather to these aspects of behavior.
Diurnal activity patter~s changed markedly over short periods of
time. Habitat use was strongly related to activity; moose tended to
use denser cover when inactive. Aggregation sizes increased from
late winter through fall and were larger in open habitats; moose in
aggregations synchronized their activity. No relationship was found
between aggregation size and weather; changes in activity and habitat
use with weather appeared to be related primarily to diurnal weather
patterns. Fall is the best time to conduct surveys, but sex-age
composition biases will result; rapid changes ir' activity patterns .. .
over short periods of time make it important to replicate censuses.
iii
...
TABLE OF CONTENTS
AB STRA.CT ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••
LIST OF FIGURES •••••••••••••••••
Page
iii
vii
LIST OF TABLES ••••••••••••.•.•••••.••.••..••.••••••••••••••••••••• viii
ACKNOWLEDGE}ŒNTS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ix
INTR ODU CTI ON • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1
STUDY AREA ••••••• 4
VEGETATION •• 6
CL l'MATE.. . . • • • • • • • . • • . • • • . • . • • • . • . • • . • • . • • • • . . . • • . • • • . . • • • • • • 7
ME TH. ODS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 10
DATA COLLECTION.............................................. 10
DATA ANAL YS IS • • • • • • • . • • • • • • . • • • • • • • • • • • • . . . • . . • . . . . . . . • • • . • • • 13
SECTION I.
Diurnal Activity Data.
Habitat Use Data •••
Weather Data ••••••
Aggregation Data •••
SEASONAL PATTERNS OF DIURNAL ACTIVITY ••••••••••••••
14
14
15
15
17
RESULTS..... ...... ... ........... .. .. . . . . . . . . .. . . ...... .. ... . . 17
DISCUSSION................................................... 17
IMPLICATIONS FOR MANAGEMENT.. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 22
SECTION II. HABITAT USE ••.•••.•.•••••.•••••.•••••••.•••.••.•••• 25
RESULTS. • • . • • . . . . • . . . . • . . . • . • • . . • • . • . . . • . . . . . . • . . . . . • . • • . • . • . 25
Habitat Use
Habitat
~n
Use in
and Sex-Age
Diurnal Patterns
Relation to Activity.
Relation to Season
Category ••••••••
of Habitat Use.
iv
25
26
29
v
Page
DISCUSSION................................................... 31
Habitat Use in Relation to Activity................ 31
Habitat Use in Relation to Season
and Sex-Age Category.......................... 32
Diurnal Patterns of Habitat Use.................... 34
IMPLICATIONS FOR MANAGEHENT. . . • • . . . . . • • . . • . . . . • . • • . • • • • . . • • . • 3 5
SECTION III. ACTIVITY AND HABITAT USE IN RELATION TO WEATHER .•.. 37
RESULTS •.•.••••••••••••. -. • • . • . • • • • • . • • • . • • • . . • • • . . . . • • • . • • • • . 3 7
Activity and Weather............................... 37
Habitat Use and Weather............................ 44
DISCUSSION................................................... 44
IMPLICATIONS FOR MANAGEMENT.................................. 50
SECTION IV. CHARACTERISTICS OF AGGREGATIONS .•••.•.•••.•.••••••• 52
RESULTS.. • . • • • • • . • • . • . • . . . . • . . . . . . . . . . . . . • . . . • . . • . . . . .. . . . . • • • 52
Seasonal and Sex-Age Differences in
Aggregation Size.............................. 52
Aggregation Size in Relation to Habitat Use........ 52
Synchrony of Activity within Aggregations.......... 55
Weather and Aggregation Size....................... 55
DISCUSSION................................................... 57
Seasonal and Sex-Age Differences in
Aggregation Size.............................. 57
Aggregation Size in Relation to Habitat Use........ 60
Synchrony of Activity within Aggregations .• ·•..••••• 61
Weather and Aggregation Size....................... 62
IMPLICATIONS FOR MANAGEMENT.................................. 62
SUMMARY AND CONCLUSIONS........................................... 64
LITERA TURE CI TED. • • • • • • • • • • • • . • • . • • • • • • • • • • • • • • • • • • • . . . . • • • • . • • • . • 6 7
PERS ONAL COMMUNICATION. • • • . • • • • • • . • • • • • • • • • • • • • • • . • • • • • • • . • • . • • . • • 7 2
vi
Page
Appendix 1. Mean number of active moose in each sex-age category
observed per 15-minute interva1 scan in each season,
Denali National Park, 1976-77 ••••••••••••••••••••••• 73
Appendix 2. Three-way chi-square analysis of habitat use,
activity, and sex-age class of moose, Denali
National Park, 1976-77.............................. 74
Appendix 3. Two-way chi-square analysis testing the hypothesis
habitat use is independent of activity among bull,
cow without calf, and cow with calf moose in Denali
National Park, 1976-77.............................. 75
Appendix 4. Three-way chi-square analysis of time of day
moose were seen, habitat use, and sex-age class in
Denali National Park, 1976-77 ••••••••.•••••••••••••• 76
Appendix 5. Two-way chi-square analysis testing the hypothesis
habitat use by moose is independent of time of
day among bulls, cows without calves, and cows with
calves in Denali National Park, 1976-77............. 77
Appendix 6. Two-way chi-square analysis testing the hypothesis
moose activity is independent of weather for
specified weather variables in Denali National Park,
1976-77 ............................................. 78
Appendix 7. Two-way chi-square analysis testing the hypothesis
the number of active bulls, cows without calves, and
cows with calves observed is independent of weather
for specified weather variables in Denali National
Park, 1976-77....................................... 79
Appendix 8. Correlation coefficients among weather variables in
Denali National Park, 1976-77 ••••••••••••••••••••••• 80-82
Appendix 9. Three-way chi-square analysis testing independence
of weather factors, activity, and habitat use of
moose in Denali National Park, 1976-77.............. 83
Appe,ndix 10. Regression analyses of weather variables in relation
to aggregation size in Denali Nation~l Park, 1976-77 84
..._
LIST OF FIGURES
Page
Figure 1. Map of the Denali National Park and Reindeer Hills
study areas........ ..................................... 5
Figure 2. Site No. 1, Denali National Park...................... 8
Figure 3. Mean monthly temperature, precipitation, and daylength,
Denali National Park headquarters, 1976-77............ 9
Figure 4. Diurnal activity patterns of moose, Denali National
Park, 1976-77......................................... 18
Figure 5. Habitat use by moose, Denali National Park, 1976-77 ••. 26
Figure 6. Diurnal habitat use by moose, Denali National Park,
1976-77............................................... 30
Figure 7. Activity of moose under various weather conditions,
Denali National Park, 1976-77......................... 38
Figure 8. Activity of bulls, cows without calves, and cows with
calves under various weather conditions, Denali
National Park, 1976-77 •.••••......•.•••......•.....•.. 42,43
Figure 9. Group sizes of moose, Denali National Park, 1976-77... 53
vii
LIST OF TABLES
Page
Table 1. Diurnal changes in observed sex ratios, Dena1i National
Park, 1976-77........................................... 19
Table 2. F-statistics from analysis separating active and
·inactive moose on the basis of continuously distributed
weather variables, Denali National Park, 1976-77 •••••••• 39
Table 3. Means and standard deviations of weather factors for
active and inactive moose in various habitat types,
Denali National Park, 1976-77 ••••••••••••••••••••••••••• 45
Table 4. F-statistics from analysis separating active and
inactive moose in various habitat types on the basis of
weather variables, Denali National Park; 1976-77 •••••••• 46
Table S. Mean sizes and standard deviations of bull and cow
without calf aggregations in Denali National Park,
1976-77 ................................................. 54
Table 6. Synchrony of activity of aggregated versus single moose,
Denali National Park, 1976-77 ••••••••••••••••••••••••••• 56
Table 7. Frequencies of group sizes observed in the present
study and other moose aggregation studies ••..••••••••••• 58
viii
ACKNOWLEDGEMENTS
This study was funded by a.contract with the Alaska Department
of Fish and Game through the Alaska Cooperative Wildlife Research
Unit. Personnel of Denali National Park provided a great deal of
logistic support.
I am grateful to a number of people for their assistance ~n
conducting and completing this study. Dr. David Klein, my committee
chairman, provided assistance and encouragement throughout the
seemingly interminable period of the study. Dr. Fred Dean was always
available to assist me in difficulties with the computer. Dr. Ed
Murphy provided the statistical skill and encouragement that helped
me find the moose again in the morass of data analysis. Dr. William
Gasaway continually asked the right questions and diligently edited
the thesis drafts.
In addition, I especially appreciate the day-to-day assistance
provided by other graduate students. Without the help of associates
like Martha Robus, Jim Hawkings, Jim Stelmock, and numerous others,
completion of the project would have been further delayed. My
husband John Rose was unfailingly patient and supportive, sometimes
in very trying circumstances, and I appreciate it.
ix
INTRODUCTION
Accurate assessment of population size and sex-age composition
of moose (Alces alces) is essential if management of this species is
to be effective. Demographie assessment has become an increasingly
important task in Alaska because of increased consumptive use of
moose by man, destruction of moose habitat by development, and
maturation of seral forest habitats due to effective wildfire
suppression.
Aerial survey from fixed-wing aircraft is the primary technique
used in obtaining moose population data in Alaska. However, many
animals are overlooked during these surveys (Timmermann, 1974).
Survey technique, characteristics of observer and equipment,
environmental conditions, and behavior of the animals influence the
sightability of moose during aerial surveys; sightability is "the
probability that an animal within an observer's field of search will
be seen by that observer" (Caughley, 1974, p. 923).
Four aspects of moose behavior were considered in this study as
potential influences on sightability of moose: seasonal patterns of
diurnal activity, habitat use, the effects of weather on activity and
habitat use, and characteristics of aggregations.
The potential importance of diurnal activity patterns of moose
to aerial survey results has been suggested previously. Gasaway et
al. (1980) found that standing moose had a much greater chance of
being observed than lying moose during aerial transect surveys in May
1
and June. Thus, diurnal variations in moose activity will affect the
number of moose seen during surveys, depending on whether a survey is
flown during a peak or low in activity. Sex and age composition
counts will also vary if there are sex-age differences in activity
patterns.
Habitat use by moose has previously been shown to be an
important factor ~n their visibility (Timmermann, 1974). Gasaway et
al. (1979), in a study of radio-collared moose, reported that habitat
selection by moose was one of the most important variables affecting
moose sightability from the air. Animals in open habitat types will
be observed more easily than those in dense habitat types.
Therefore, the precision and accuracy of population estimates will be
affected if there is differentia! diurnal or seasonal habitat use.
In addition, composition estimates will be unrepresentative if
sex-age classes of moose make differentia! use of habitat types.
The influence of weather on pilots and observers during aerial
surveys has been reported previously (e.g. LeResche and Rausch,
1974). However, the effect of weather on moose behavior has been
investigated little. If moose alter either their activity patterns
or habitat use in changing weather conditions, survey results may be
affected. The set of conditions under which surveys may be flown is
limited 1 bu~ moose may alter .their behavior within these limits.
Finally, aggregation characteristics of moose may influence
their visibility. Size, composition, location of, and synchrony of
activity within an aggregation are important factors influencing the
-
2
l
accuracy of population and sex-age composition estimates.
The study objectives were:
1) to determine the ~nfluence of environmental factors,
including season, time of day, and weather on moose activity,
aggregation patterns, and habitat use,
2) to determine the variation in activity, habitat use,
and aggregation characteristics among sex and age classes of
moose;
3) to predict, qualitatively, optimum daily and seasonal
timing of aerial surveys and predict biases in estimates of
total numbers and sex-age composition of the population.
3
STUDY AREA
The study was conducted primarily ~n the eastern portion of
Denali National Park, Alaska, formerly Mt. McKinley National Park
(Fig. 1). Denali National Park was selected as the study area for
this project for a number of reasons. At the time the study was
undertaken, moose numbers in interior Alaska were generally very low,
and the Park provided a large, relatively dense population which was
habituated to humans. In addition, the presence of the Park road
permitted easy access to areas with large numbers of moose.
Observations of large areas from single vantage points were possible.
In the eastern portion of the Park, the "Outer Range" lies north
of and parallel to the main mountain system. Between the two systems
lies a broad valley, the floor of which is at elevations of
600-900 m. Most moose habitat ~n the eastern part of the Park lies
either in this valley ~ along the river systems that transect it.
The Park road runs through the valley, making moose habitat easily
accessible to observation.
Moose were abundant in the study area. The approximate density
of moose seen during November aerial surveys has been estimated at
2 0.3-0.6 moose per km between 1974-1980 (Tankersley, 1981). Observed
calf:cow ratios during ~ovember aerial surveys, 1974-78, have ranged
from 8:100 to 19:100. Bull:cow ratios in the same period have ranged
from 26:100 to 45:100 (Troyer, 1980).
Observations were made in March 1977 in the Reindeer Hills,
4
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Figure 1. Map of the Denali National Park and Reindeer Hills study areas.
which lie approximately 50 km southeast of the Park study sites (Fig.
1). The vegetation and climate in this area are similar to those
described below for the Park, but with increased precipitation.
VEGETATION
At the lowest elevations in the Park, vegetation consists
primarily of boreal forest communities, with white spruce (Picea
glauca) dominating, and black spruce (Picea mariana) in wetter
sites. There are also large stands of aspen (Populus tremuloides)
near the eastern boundary, and scattered balsam poplar <1.
balsamifera) along major drainages.
At higher elevations, vegetation grades into the upland climax
community described by LeResche et al.(l974), made up of the dominant
shrub birch (Betula ~and~· glandulosa), willow (Salix ~.), and
a variety of smaller shrubs and forbs. This vegetation is replaced
by alpine tundra communities at higher elevations. Willow~ are most
abundant on wet sites--along streams and on poorly drained
north-facing slopes. Vegetative communities are more fully described
~n Viereck and Dyrness (1980).
Moose were found throughout the boreal forest and upland climax
communities. I made most observations in the upland climax areas or
in the transitional zones between forest and shrubland because moose
were much more visible in the more open areas.
Two moist north-facing slopes within the upland climax community
were heavtly usE~ by moose, particularly in summer (Sites 1 and 2 on
6
7
Fig. 1). Both provided a diversity of habitat types, including
abundant willow growth and patches of spruce and herbaceous cover
(Fig. 2). Moose were easier to pbserve at Site 2 because willows
were shorter and spruce more scattered than at Site 1.
CLIMATE
The climate of Denali National Park has been described
previously (Murie, 1944; U. S. Dept. Comm., 1970). Temperatures
during the field portions of my study were generally above normal
except in the fa11 of 1977; the winter of 1976-77 was one of the
warmest on record (Fig 3a). Temperatures during the March-November
0 0 study period ranged from 30.0 C to -28.9 C. Precipitation was
variable (Fig. 3b); mid-summer was wet in 1976, but early summer and
fall were dry. In 1977, spring and fall were wet, but the summer was
very dry.
Photoperiod varies from a low of approximately 4 hours 10
minutes of sunlight on the winter solstice to a high of 21 hours 10
minutes on the summer solstice (Fig. 3c). Continuous sunlight or
civil twilight, when the sun is six degrees or less below the horizon
(see Se1kregg, 1974), occurs from mid-May until late July.
Figure 2.
8
Site No. 1, Denali National Park, showing diversity of habitat
types present.
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:I: t Feb Apr Jun Au~ Oct Dec! Feb Apr Jun Auo Oct Dec 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Jan Mar May Jul Sep Nov Jan Mar ._.ay Jul Sep Nov
1976 1977
9
Figure 3. Mean monthly temperature (Nat. Oceanic Atmos. Admin.),
precipitation (Nat. Oceanic Atmos. Admin.), and daylength (Univ.
Alaska, Geophysical Institute), Denali National Park head-
quarters, 1976-77.
METHODS
DATA COLLECTION
Field work was conducted from 7 July through 6 November in 1976
and in Marchand 12 May through 8 November in 1977. I observed moose
primarily at one of two sites (see Study Area). When no moose were
visible in these two areas, I located moose by driving along the Park
road and stopping every few hundred meters to scan the surrounding
area with binoculars. I began observations when I located one or
more moose. Observation periods lasted about 8 hours, unless
disturbance or reduced visibility caused me to terminate observations
earlier. Observation periods were staggered from day to day to
adequately sample all hours with sufficient light for using a
spotting scope. Disturbance was rarely a problem because most moose
under observation were 1 km or more from my observation point and the
Park road.. Howeve,r, some observations have been include<'\ of moose
close to humans if they did not appear to be disturbed; most of these
observations were made during the fall when rutting groups commonly
aggregated near the road.
Identification and activity data were recorded every 15 minutes
using the instantaneous scan method (Altmann, 1974). The following
information was recorded for each moose observed:
1) Daily individual identification number. Each animal
was assigned a number for the day.
2) Long term individual identification number. These
10
numbers were assigned to animals seen on two or more days; most
identifications were of bulls, whose antler configurations made
them identifiable at a distance.
3) Daily group identification number. Each group (also
referred to as "aggregation" when consisting of more than one
animal) was assigned a number for the day. My working
definition of an aggregation was similar to Sigman's (1977, p.
48): "a group [of two or more animals] which fed and travelled
together ••• often staying together for several days." Moose in
an aggregation usually remained within several meters (2-20 m)
of sorne other member throughout an observation period, and
showed similar direction and timing of movements.
4) Long term group identification number. These numbers
were assigned to groups seen on two or more days.
5) Number of animals in the group.
6) Sex-age category of individuals. I recorded six
categories: bull, cow without calf, cow with calf(s),
yearling, unknown cow, and unknown sex and/or age.
11
7) Activity. A moose was defined as active when it was on
its feet and as inactive when lying clown. Activity was recorded
on individuals except when large group sizes made it impossible
to keep track of individuals; in those instances I recorded the
number of moose involved in each activity.
8) Habitat type. The habitat type each moose was in at
the time of a scan was short open (herbaceous or shrub
vegetation less than 2 m tall), tall shrub (shrub more than 2 m
tall) or forest (scattered or dense spruce, or rarely,
deciduous).
9) Time of Day (Alaska Daylight Time).
10) Date.
Twelve environmental parameters were recorded every 30 minutes:
1) Temperature (°C) was measured in the shade 0.5-1.0 m
above the ground.
2) Wind speed (km/hr) was measured with a Dwyer wind
meter.
3) Wind direction was recorded as one of the compass
octants.
4) Relative humidity was measured with a Weksler sling
psychrometer.
5) Barometric pressure (mm Hg) was measured at the
observation site and later standardized for 2000 feet (610 m)
elevation.
6) Level of insect harassment was estimated from behavior
of the animals (such as frequency of ear twitching) and scaled
0-3: O=none, 3=heavy.
7) Precipitation type was recorded as: none, rain, snow,
mixed rain and snow, or sleet and hail.
8) Precipitation intensity was recorded on a scale of
0-3: O=none, 3=heavy.
9) Cloud cover was estimated to the nearest 10%.
12
13
10) Local cloud height was estimated by relationship to the
height of mountains in the area.
11) Sunniness at the location of the observed animais was
recorded as sunny, partly sunny, or shaded.
12) Incident lumens/m of light were measured with a Gossen
Luna-Pro light meter at my observation site.
DATA ANALYSIS
The study period was divided differently in Section I than in
Sections II, III, and IV. In Section I, the study period was divided
into nine seasons: late winter (10-12 March), pre-calving/calving
(12-31 May), post-calving (1-15 June), early summer (16-30 June),
mid-summer (1-31 July), late summer (1-31 August), pre-ru~ (1-21
September), rut (26 September-30 October), and post-rut (5-8
November). In Sections II, III, and IV, severa! of these time
periods were combined for simplicity, and four seasons were
considered: late winter (10-12 March), spring (1-31 May), summer (1
June-31 August), and fall (1 September-30 October); November data
were not included because of small sample sizes.
Data were summarized and analyzed by season in each section with
the aid of the Statistical Package for the Social Sciences (Nie et
al., 1975) computer programs.
·,
14
Diurnal Activity Data
The mean number of active moose per scan was calculated by
dividing the total number of observations of active moose in a given
hourly period (e.g. 0900-0959) within each season by the total number
of scans made in that hour through the season. Since there were four
sc ans in each hourly period each day, one moose could contribute four
times to the activity count for that hour, if it were active at, for
example, 0900' 0915' 0930' and 0945. If it were active at 0900 and
0915 and then bedded down, it would contribute twice to the activity
count. Portions of the diurnal curves which were generated from
fewer than four scans have not been included.
Approximate times of sunrise and sunset are indicated on the
relevant figures; these figures are only approximate because
daylength was changing rapidly (± 6-8 minutes per day) (Fig 3c.)
during much of the study period. The actual hours of insolation on
the study area were generally much less than these figures indicate,
because the surrounding mountains blocked the sun early and late in
the day.
Chi square analysis was used to test the significance of diurnal
changes in the proportions observed of bulls, cows without calves,
and cows with calves.
Habitat Use Data
Two-and 3-way chi-square analyses were used to test differences
~n habitat use among different sex-age classes~ activities, and times
F
of day. Late winter data were excluded because of small or zero
expected values.
Weather Data
Correlation analyses were performed to determine zero-order
correlations among continuously distributed weather factors.
15
The relationship between activity and weather was examined using
2-way chi-square analysis; weather data were grouped into several
categories for each weather factor. Sex-age differences in activity
with weather were tested with chi-square analysis. Correlation of
mean percentage of moose active per day with rate of change of
barometric pressure was tested using linear regression; data were
selected from several periods of rapidly increasing or decreasing
barometric pressure throughout the study period.
Interdependence of activity and weather factors with habitat use
was tested with 3-way chi-square analysis. Means of each weather
factor were determined for active and inactive moose in each habitat
type; analyses of variance were used to test the significance of
differences among these means.
Aggregation Data
Because I was sometimes not aware of all moose within an
aggregation until I had been observing the a6gregation for an hour or
more, new data files were used when analyzing the aggregation data;
these files consisted of either all records for each group after it
reached its maximum size for the day, or a subsample of this file
16
consisting of one record per group per day. In this way an
aggregation of six moose, for example, will not appear in the
analyses as an aggregation of four or five just because one or more
moose were initially invisible (usually because they were inactive in
dense cover).
The independence of aggregation size and activity was tested
using 2-way chi-square analysis.
Multiple regression was used to determine which weather factors,
excluding wind direction, best explained variation in aggregation
size. Chi square analysis was used to test the independence of wind
direction and aggregation size.
SECTION I
SEASONAL PATTERNS OF DIURNAL ACTIVITY
RESULTS
Diurnal activity patterns changed dramatically through the study
period (Fig. 4). Activity levels were most uniform through the day
in mid-and late summer, and showed the largest peaks and troughs in
the following period, pre-rut.
The diurnal ratios of bulls to cows without calves to cows with
calves during each season were highly variable (Table 1, Appendix
1). Although these differences were statistically significant, no
diurnal pattern of differences was apparent.
DISCUSSION
" Direct comparisons of my results with those of ether moose
activity studies are difficult for three reasons. First, most ether
studies pooled data for the entire summer, thereby masking any
changes in activity patterns such as I observed in my study. Second,
several of the ether studies involved moose use of aquatics (e.g.
Murie, 1934), which were not available to moose on my study area.
Heavy summer use of aquatics may be related to mineral
supplementation of the di~t (Jordan et al., 1973). If so, activity
patterns in aquatic areas may be simi1ar to activity patterns at
mineral licks. These activity patterns may be qu~te different than
those of moose not in the vicinity of a lick. Activity patterns of
17
c c
(.J en
c > ...
CD -c
CD -~ c .
10
...
CD o.
"0
CD > ...
CD en
..Q
0
CD en
0
0
:E
CD > -(.J
a.
3
2
b.
3
2
Pre-Colving/Colving
Post-Colving
e.
:~
4 f • Pre-Rut
3
2
5
4
3
2
~ o~~._._._~~~._~~~ -o o~~~~._~~~~~~~~ ...
CD
..Q
E
~ z
c c
CD
:E
d •
3
2
Mid-Summer ~-ittJWAâ
1
1. Lote Winter
0~'/y)y' 1 Wâ
0600 1200 1800 2400 0600 1200 2400 1800
Ti me of Day (Alaska Daylight Saving Tl me)
18
Figure 4. Diurnal activity patterns of moose, Denali National Park,
1976-77. Hours of twilight or darkness are shaded. Samples
based on less than four scans have been excluded.
....._
~--~~-00~---·-~~--~-·~-,--..,---~-~--·---
Table 1. Diurnal changes in observed sex ratios, Denali National Pnrk 1976-77. Resttlls of chi-squnre ana1ysis testing the
independence of observed sex composition and time of day nre indicated (*p < 0.01, **p < 0.001). B; btll1s, C; cows
without ca1ves, CC ; cows wlth calves; samp1e size of cows wlthout calves is indicated ln parentheses fo1lowing enclt
ratio.
B:C:CC
Pre-ca1ving/
Ti me Calving Post-calving Early Summer Mid-summer Late Summer Pre-rut Rut
-·------· -----
x2 =72. 713(15)** x2 =38.819(15)** x2 =35.653(15)* x?=54. 702(15)** x 2=39. 371(15)** x2 =62. 381( 15) ** x2 =3. ,,99(12)
0300-
0645 4 6 7 : 1 00: 6 7 (3) 140:100:0(5) 62:100:15(52) 113:100:50(46) 27 :100:9(33) 38:100:8(39)
0700-
1045 95:100: 63( 41) 29:100:37(41) 37:100:29(62) 164:100:29(76) 61:100: 15(105) 52:100:26(91) 15: 100:2(334)
1100-
1445 80:100:63(30) 42:100:22(36) 102:100:51(49) 104:100:15(204) 66:100:23(167) 24: 100:43(70) 15:100: 2(164)
1500-
Hl45 14:100:145(22) 3 2: 100: L 7 ( 66) 54: lOO: 32 (91) 98:100:45(247) 66:100:26(182) 10:100:9(157) 16:100:1(444)
1900-
2245 0:100: 51(35) 300:100:0(5) 212:100:41(17) 134 :100:60(86) 20:100:18(147) 42:100:0(24) 20:100:0(5)
t-'
\.0
moose at mineral licks in the Park 20 km from my study area were very
different from what I observed (Tankersley, 1981). Third, the light
regime at high latitudes is very different than at 1ower latitudes,
and may function differently as a Zeitgeber (photoperiodic
indicator). Geist (1963) hypothesized that light synchronized the
morning and evening activity peaks of moose in British Columbia. In
Denali. there is one continuous dusk to dawn twilight period each
night in the summer (see Study Area), and photoperiod fluctuates
radically through the year; activity was not as closely linked to
light levels (Fig. 4) during most seasons as in some other studies.
Given these limitations, it still may be useful to compare
observed moose activity in Denali with results of other studies.
In spring and early summer (pre-calving/calving, post-calving,
and early summer), moose in my study exhibited three peaks ~n
activity, although the timing and intensity of these peaks changed
markedly through the period (Fig. 4a-c). Four activity peaks were
observed by Geist (1963) in May and June; he suggested light
synchronized the dawn and dusk peaks and an endogenous feeding rhythm
synchronized the peaks in between. My data showed a suggestion of a
fourth peak early in the morning during pre-calving/calving, which is
not included in the figure because of a small sample size. If this
fourth peé~ was real, then a series of evenly spaced, approximately
equal-sized peaks (Fig. 4a) exists during pre-calving/calving, and
does suggest a regular feeding rhythm. In the next two periods,
however, only three peaks were seen (Fig. 4b-c).
20
From early to late summer, there was a flattening of the
activity curves of moose in the Park. Early summer activity patterns
closely resemble those reported in summer studies by Belovsky and
Jordan (1978) and Joyal and Scherrer (1978). Moose in those studies
showed three peaks in activity: morning and evening peaks, and an
afternoon peak related to aquatic feeding. Moose in my study were
also active in the afternoon, despite the absence of licks or
aquatics (Fig. 4c). Later in the summer, activity was higher in the
afternoon than in late morning, but no distinct peak was apparent
(Fig. 4d-e). Activity levels were highest morning and evening as in
other studies (e.g. Best et al., 1978), but sharp peaks were not
apparent after early summer.
Moose activity in the Park was more crepuscular in the fall than
at any other time during the study period (Fig. 4f-g). During
pre-rut, activity levels were much higher around dawn and dusk than
'1
~
21
at other times of the day; duri11g rut, activity was generally high 1.n
the afternoon, but was at maximum levels around dawn and dusk. In
contrast, Best et al. (1978) found activity was greater during the
day than around dawn and dusk in the fall; they suggested greater
daytime activity in fall reflected greater social contact in relation
to the rut. In my study, however, most rut-related behaviors were
crèpuscular, which has been observed elsewhere as well (Rykovskii,
1965). Activity during this time appeared to be strongly linked to
light eues. Intensification of activity peaks and troughs was also a
consequence of large aggregation sizes (see Section IV); to the
22 :
extent that moose in an aggregation synchronize their activity with
other members, peaks and troughs will be more sharply delineated than
when animals are more uniformly dispersed.
Winter data (post-rut and late winter) from this study suggest
activity differed in early and late winter. Post-rut observations
suggested similar dawn and dusk peaks in activity (Fig. 4h) to those
reported elsewhere (Best et al., 1978; Geist, 1960). In late winter,
however, there were multiple peaks during daylight hours; moose
activity has been found to be extremely variable in timing and
duration from day to day in late winter on the Kenai Peninsula,
Alaska (Sigman, 1977).
The one consistency in this pattern of changing diurnal activity
u that activity always approached its lowest levels late ~n the
morning, near midday. This was true throughout the study period
(Fig. 4). Occasionally (e.g. pre-rut) activity was equally low at
some time in the afternoon; generally late morning represented the
time of minimum moose activity.
IMPLICATIONS FOR MANAGEMENT
The ideal moose activity pattern for aerial survey purposes
would be an extended peak of three or four hours during which all
animals are active. The number of moose counted would thus be
maximized. Because all sex-age categories would be standing, all
would be counted ~n proportion to their occurrence in the population
(
(barring other differences in behavior, such as differentia! habitat
use).
Unfortunately, this ideal situation does not occur. At no time
during the day were all moose active. In addition, activity curves
rose and fell sharply over short periods of time except in mid-to
late summer, when vegetation density greatly reduces visibility of
moose. At other times of the year, one may expect a variation of 3-
to 7-fold in the number of moose active throughout the day (Fig. 4).
Conditions for aerial surveys were relatively good during
pre-calving/calving when two fairly broad peaks in activity occurred
during hours with good lighting (Fig. 4). From 0800-1000 and
1300-1600, approximately equal numbers of moose appeared to be
active. One could expect to see only 1/4 to 1/3 as many active
animals during the intervening 1ow. These two periods meet the
conditions of two 3-hour search periods recommended by Timmermann
(1974) for aerial surveys. Bu1l:cow ratios were lower in the
afternoon than in the morning, but I be1ieve this was due to a
sampling anomaly.
In the fall, the best time to conduct surveys appears to be ~n
the afternoon during rut. Then activity was high and increasing in
the afternoon except for a brief period around 1400 h. Low light
levels around dawn and dusk preclude surveys at these times, although
activity was highest then, and there were no 3-or 4-hour periods
when relatively stable numbers of moose were active.
During post-rut, surveys must be conducted during midday because
23
of low light intensity; this period coïncides with low activity of
moose. However, good snow caver increases the sightability of
inactive moose relative to that of inactive moose during snow-free
periods (Gasaway et al., 1979, 1980).
Since activity appears to be low during late morning throughout
much of the year, survey work during this period should be avoided.
If surveys are conducted during these hours, it should be with the
awareness that the number of moose seen will probably be law.
The difference in photoperiod due to the high latitude and the
absence of aquatics or mineral licks on the study area probably limit
the applicability of these results to many other areas. Results from
this study will be most useful for other high-latitude moose
populations, and in habitats where aquatics or mineral licks are not
common, or at those times when lick and aquatic use is not heavy.
Variability in results of other studies is probably due in part to,
differences in these factors.
24
RESULTS
SECTION II
HABITAT USE
A strong bias existed in this study toward sighting moose in
open habitats. Because these moose were much easier to observe, they
are overrepresented relative to those using tall shrub or forest.
While observed habitat use is not, therefore, an accurate
representation of habitat use per ~' it should provide a useful
relative index of differences in habitat use under various
conditions. These include differences by season, sex-age category,
activity, and time of day.
Habitat Use in Relation to Activity
A strong interdependence existed among habitat use, activity,
and sex-age category. The null hypothesis that these factors were
mutually independent, and independence of each factor from the
others, was rejected in every case (p<O.OOl) except one--activity was
independent of habitat or sex-age category in fall (Appendix 2).
Observed habitat use varied between active and inactive moose of
the same sex-age category in most seasons (Fig. 5, Appendix 3). In
spring, bulls used short open habitat types more when they were
active than when bedded down; conversely, tall shrub and forest were
used more by inactive bulls. Cows without calves showed no
significant differences in habitat use in relation to whether they
25
Q) o.
~ -0 -..0
0
SPRING
100
80
60
40
20
0
J: SUMMER
Bu lis Cows w/o Calves Cows w/Calves
87 190 131 54
0 Forest f2] Toll Shrub Il Short Open
~ 1944 1255 689 2098 14 74 624 595 443 152 (.) 100 0
Q)
c:
Q)
Cl)
0
0
~ -0
Cl)
c:
0 -0 > ...
80
60
40
20
0
~ FALL ..0
0 100 -0
~ 80
0
60
40
20
0
Toto 1 =Active+ Ina ct ive
435 309 128
-(.)
<t
-(.)
0 c: -
817 555 262
0 ··-~
Q)
> -(.)
<t
Q) > -(.)
0 c:
59 49
Q)
> -(.)
<t
10
Q)
> -(.)
0 c: .....
26
Figure 5. Habitat use by rnoose, Denali National Park, 1976-77. Sarnple
sizes are indicated above each bar. Results of chi square
analysis testing independence of habitat use and activity are
indicated where significant (* p < 0.01, **p < 0.001).
27
were active or inactive, although inactive cows used forest more than
active ones. Cows with calves, exhibiting a very different use
pattern, used tall shrub habita~ types when they were active and
short open habitats when inactive.
In summer, active bulls used short open habitats more than
inactive bulls; conversely, tall shrub was used more by inactive
bulls. Active and inactive cows without calves displayed a habitat
use pattern similar to that I observed for bulls. Short open habitat
types were used more by active, and tall shrub more by inactive cows
with calves.
In fall, bulls and cows without calves used short open habitat
types much more when active and tall shrub more when inactive. There
was no significant difference between habitat use by active and
inactive cows with calves, although the former were seen more in
forest and the latter in short open habitat types.
Habitat Use in Relation to Season and Sex-Age Category
Observed habitat use patterns changed seasonally within each
sex-age category (Fig. 5), and among sex-age categories as well 1n
spring (X 2 =123.328, df=4, p<O.OOl) and summer (X 2=34.812, df=4,
p<O.OOl) but not as much in fall (X 2=12.825, df=4, p<O.OS).
Only active moose were considered in the statistical testing of
sex-age differences in activity for two reasons. First, earlier
analyses demonstrated that activity was dependent on habitat use and
sex-age category; thesé interrelationships are not a problem when
only active moose are considered. Second, active moose are much more
likely to be seen during aerial surveys than bedded moose (Gasaway et
al., 1980); therefore, examination of habitat use by active animals
can be used to predict which sex-age categories of moose will be most
easily seen.
28
In spring, observed habitat use varied significantly among
bulls, cows without calves, and cows with calves. Bulls were seen in
forest more than any other habitat type; in contrast, cows without
calves were most often observed in short open habitat types. Cows
with calves were observed almost equally often in tall shrub and
short open habitats in spring.
Observed habitat use patterns were much different in summer than
1n spring. All sex-age categories were most often seen in tall shrub
habitat types. Bulla, however, still used forest more than cows;
cows with calves made greater use of tall shrub areas than bulls or
cows without calves.
In fall, observed habitat use was similar among all sex-age
categories. All made greater use of short open habitat types than in
summer. Cows with calves continued to make greater use of tall shrub
than bulls or cows without calves.
In late winter (March), most cows with calves were observed in
tall shrub, and most other moose'were in forest; the data were not
statistically analyzed because of small sample sizes.
Diurnal Patte.!,!!2 of Habitat Use
There was a strong interdependence among habitat use, time of
day moose were seen, and sex-age category. The null hypotheses of
mutual independence and independence of each of these factors from
the ethers were rejected in every case (p<O.OOl) (Appendix 4).
Habitat use by moose was linked to time of day in spring,
summer, and fall for each sex-age category (p<O.OOl) (Fig. 6,
Appendix 5). In late winter, habitat use was independent of time of
day.
In spring, diurnal patterns of habitat use varied among bulls,
cows without calves, and cows with calves. Bulls primarily used
forest early in the morning; use of forest declined later in the day,
and use of tall shrub increased. No bulls were observed in late
afternoon or evening. Cows without calves, in contrast, were
observed in short open areas early in the morning; they made greatest
relative use of forest around midday. Use of tall shrub was greatest
~n the evening. Cows with calves also used short open areas the most
in the morning, while tall shrub use increased steadily with highest
use levels in late evening.
I~ summer, diurnal patterns of habitat use were similar among
bulls, cows without calves, and cows with calves. All moose used
forest primarily around midday and short open areas primarily early
~n the morning and late in the evening.
All three categories of moose made heavy use of short open
habitat types early in the morning in the fall. Bulls and cows
29
30
Bulls Cows w/o Calves Cows w/Calves
SPRING
100
80
60
40
Cl) a.
:>. 20 1---0 0
~ 0 Forest 0 Toll Shrub • Short Open 0
:I: SUMMER
.s::. 137 210 723 588 190 143 365 770 652 173 34 78 231 214 41 (J
0 100 Cl)
c:
Cl) 80
en
0 60 0
~ -40 0
en c:
0 20 -0 > 0 ...
Cl) en ..c FALL 0 -71 23 16 18 20 0 100
~ 0
80
60
40
20
0 ... ... "' .. .. .. s:: .. .. .. ... "' s:: .. .. .. "' s:: ~ .. .. CD "' .. ... .. .. s:: .. s:: .. ... ... s:: ... s:: CD s:: ... s:: CD s:: CD s:: s:: ' s:: s:: ~ If' s:: ~ (\j
,.,., CD (\j (\j (\j (\j ~ (\j (\j (\j ,.,., (\j
+1 + +1 r? +1 + +1 1 +1 +1 + +1 1 +1 +1 G> -G> G> Q> >---Q> >--; G> ... >--; -., ., Q> "' .. 0 G> .. 0 Q> 0 G> "' "CC "' "' .. ... "CC "' ... "CC ., "' c ... c c c ... c c c "0 c c c "0 c "0 c ::0 ::0 ::0
::0 ::0 ::0 ::0 ::o· ::0 ::0 ::0 ::0 :i (/) (/)
(/) (/) :E (/) (/) (/) (/) :E (/) (/) (/) (/)
Ti me of Day
Figure 6. Diurnal habitat use by moose, Denali National Park, 1976-77.
Sample sizes are indicated above each bar. The midday period
has beel:, incorporated in the adjacent periods because of
shorter daylength.
without calves also used these areas heavily in the evening. Cows
with calves, on the ether hand, used tall shrub areas in the
afternoon and evening.
DISCUSSION
Habitat Use in Relation to Activity
Visibility of moose is dependent on their choice of habitat as
well as their activity. Gasaway et al. (1979) found that, during
aerial survey work in winter, trees acted as visual barriers to the
observer in the case of beth standing and lying moose, while shrubs
were a visual barrier mainly for lying moose. In addition, tall
shrubs are effective visual barriers for all moose when vegetation is
leafed out in summer. Thus visibility of moose is affected not only
by activity and habitat use considered separately, but by the
interactions of these two aspects of moose behavior as well.
Moose in the present study did select different habitat types
for certain activities. Moose tended to feed in more open areas and
move into denser cover for bedding. Commonly, a moose in an open
area slowly made its way toward a patch of taller, denser vegetation
in. the last few minutes of a feeding period and bedded down there.
Cows with calves in spring were the major exception to this pattern,
but I believe this represents a sampling artifact. The many
observations were of only a few cows, visible because they bedded in
small islands of open habitat and moved into nearby tall shrub to
31
feed. Of other moose, not all moved into denser cover to lie down;
in many instances a moose feeding in the open bedded down in the same
area. Murie (1934) and McMillan (1954) found no difference in lying
in short open or dense habitat types.
Habitat Use in Relation to Season and Sex-Age Category
Sex-age differences in habitat use were observed in spring in
the present study; results from other studies have varied. While I
observed bulls in the spring using forested areas more and open areas
less than expected values, Berg (1971) reported bulls used open areas
the same as expected values in Minnesota. Gasaway et al. (1980)
found bulls selected aquatic-herbaceous habitats and avoided tall
canopies. Gasaway (pers. commun.) has suggested that the opposite
behavior he and I have observed in bulls in two interior Alaska study
areas may be a consequence of the different forest types in these
areas. Forest patches on my study area are widely spaced white
spruce with an abundant willow understory. In Gasaway's study area,
however, very dense black spruce may discourage use by bull moose
because of possible injury to velvet-covered antlers. I found cows
without calves making greatest use of open habitats, while Berg
(1971) and Gasaway et al. (1980) both found cows without calves
avoided open areas. Cows with calves used tall shrub areas more than
expected in the present study; Gasaway et al. (1980) also found that
cows with calves selected tall canopies. In Minnesota, however, cows
with calves used open areas (Berg, 1971), which suggests the high use
32
levels of open habitat types by cows with calves that I observeè
during spring (Fig. 5) may be a real phenomenon and not the sampling
artifact I suspected. Cows witb calves I observed in open areas were
usually bedded in a small opening surrounded by tall shrub. Such a
position still provides the benefits of caver in tall shrub, but the
opening might aid the cow in active defense of her calf.
Variation in habitat use by sex-age category was similar Ln
summer to spring despite the overall greater use of tall shrub, i.e.
proportionately greater use of forest by bulls, short open areas by
cows without calves, and tall shrub areas by cows with ca1ves.
LeResche (1966) be1ieved bulls used mature deciduous caver
disproportionately in his study area, but Knowlton (1960) and Coady
(1976) reported greater use of short open habitats by bu11s in
summer.
All types of moose showed similar habitat use patterns in fall
Ln the present study, with use of short open habitat types
predominating. Similarly, Coady (1976) and Lent (1974) found moose
preferred open habitat types in fall. Cows with ca1ves used tall
shrub slightly more than ether sex-age categories. In Minnesota,
Berg (1971) found that cows with calves used tall mature habitats
four times as much as short open habitats during rut, while bulls and
cows used the two equally. Identical habitat use patterns by bulls
and cows without calves during the present study probably resulted
from their close association in large aggregations at this time.
In late winter, moose in this study and others used ta11 dense
33
habitat types (e.g. Coady, 1976; Gasaway et al., 1977; Berg, 1971).
Use of dense habitat types has been associated with less snow than in
open areas (e.g. Krefting, 1974) and may also be a reflection of
reduced feeding at this time (Gasaway and Coady, 1974).
Cows with calves showed a consistent difference in habitat use
throughout the study period relative to bulls and cows without
calves; they made greater use of tall shrub. This habitat type
offers excellent cover from predators, and may facilitate avoidance
of ether moose as well. LeResche (1966) reported cows with calves
used a dense area of scrub birch and aspen not used by any ether
sex-age category, and Peek (1962) reported more cows with calves than
cows without calves using dense cover in summer.
Diurnal Patterns of Habitat Use
In bread terms, patterns of diurnal habitat use followed diurnal
activity. This is what one would expect, given that habitat use was
dependent on activity for most sex-age categories in most seasons.
Use of short open habitats tended to be highest (Fig. 6) when
activity levels were highest (Fig. 4), and use of forest and tall
shrub combined was highest when activity levels were low. This was
most evident in summer; I always thought I saw more moose early and
late ~n the day, despite the absence of sharp activity peaks (Fig.
4d-e). Diurnal habitat use patterns help explain this phenomenon.
In fall, high levels of use of open habitats also coincided with
activity peaks (Fig. 4f-g). In spring, ther was not a clear
coïncidence of habitat use and diurnal activity, probably because the
activity pattern in spring (Fig. 4a) was characterized by three
evenly spaced, moderate, and equal-sized activity peaks, rather than
crepuscular peaks.
IMPLICATIONS FOR MANAGEMENT
The dependence of habitat use on activity, season, sex-age
category, and time of day indicates that bias will occur whenever
surveys are flown.
The tendency of moose to use open habitats when active means
active moose are easier to see than if no activity-habitat
interaction occurred. Inactive moose will be very difficult to see
because of their tendency to lie down in dense vegetation, as well as
because of their inactivity. Diurnal habitat use patterns reinforce
the activity-habitat interaction; therefore, an attempt should be
made to conduct surveys during activity peaks, when the greatest
number of moose will be active and in the open. Timing in terms of
activity peaks has been discussed previously (see Section I).
Bias occurs as a result of differential habitat use by various
sex-age categories of moose. Cows without calves will tend to be
overrepresented in composition counts except in fall, because of
their greater use of short open habitats. Bulls, in contrast, will
tend to be underrepresented except in fall surveys; their greater use
of forested habitat types in spring and summer makes a greater
proportion of them very difficult to see. Cows with calves will
35
36
probably be underrepresented during surveys flown in spring, summer,
or fall, because of their greater use of tall shrub areas.
Applicability of results of the present study to those in ether
areas will be variable, depending on how closely moose habitats and
activity patterns parallel those on the Denali study sites. Wide
variation has existed in past studies, probably due in part to
variability ~n habitats and activity patterns.
SECTION III
ACTIVITY AND HABITAT USE IN RELATION TO WEATHER
RESULTS
Activity and Weather
Moose activity levels under different weather conditions were
highly variable (Fig. 7, Appendix 6).
In spring, activity of moose was generally independent of
weather conditions, although activity was greater at low wind speeds
(Fig. 7, Appendix 6, Table 2) and high temperatures (Fig. 7, Appendix
6). Wind speed and temperature both tended to increase diurnally
(Appendix 8a). The diurnal activity pattern probably accounts for
greater activity at higher temperatures; no activity peak was
observed early in the morning when temperatures were low, but there
was an activity peak in the afternoon when temperatures were near
maximum (Fig. 4a). Activity was lower at high wind speeds despite
the diurnal pattern of increasing winds; this suggests that moose
modified their activity as a direct response to wind speed.
In summer, statistically significant relationships existed
between moose activity and virtually all weather factors measured
(Fig. 7, Appendix 6), but it is questionable whether these
relationships are all biologicully significant. Activity was highest
in conditions of northerly or westerly winds at low to moderate
speeds, low cloud cover, low light intensity, moderate humidity
(which, along with insect harassment, was considered only in summer,
37
Q)
en
0
0
~
-,::)
Q)
> .....
Q) en .c
0 -0
::0..
>
-c:
Q)
(J .....
Q)
Cl.·
100 [ a.
80 !-, ... ..<>-·---~
60 .,..r. ',.,_ / \
', / "\~'o··
40~ ... ·....----.....,
-Sprrng
20 ---·-Summer
7·14 23·30 ---Foll
0 L...-t--+--+---+--1 • 20s ns 100
0·6 15-22 31 +
Wind Speed (k ph) o n>IOO
100 fe.
80 t/,A',,, ~
fi ~............ .--~ .. ---o....... .,. .....
60 ' .... ,~. '·~·
40 v··
20
0
-5-0 5-10 15-20 >25
-10--5
60
0 .75-3 12-50 >200
o-.75 3·12 50-200
Light Intensity (11m2 )
100 r g . ... ,
...... "'Q.,
80 ',,
''b..-,.c,.".,..o..._·"''o.. ..
~·-·-o'· """0... -·'"'0--·-·-o ~---~-60
40
20
735-740 745-750 755-760
0'---+--+-1---1---+-
<735 740·745 750-755 760-765
Barometric Pressure (mm Hg)
N
E
s
Wind Direction
0-9 20-39 60-79
Cloud Caver (%)
f.
0 20 40 60 80 100.·
Relative Humidity (%)
0 1 2+3
Precipitation Intensity
r t
38 1
\ t
Figure 7. Activity of moose under various weather conditions, Denali
National Park, 1976-77. When two weather categories were
combined because of small sample size, the data point has been
located between the two categories. Results of chi square
analysis testing independence of activity and weather are
indicated where significant (*p < 0.01, **p < 0.001).
39
Table 2. F-statistics from analysis separating active and inactive
moose on the basis of continuously distributed weather
variables, Denali National Park, 1976-77 (*p < 0.01,
**P < 0.001). Sample sizes in each season are indicated
in parentheses.
Spring Summer Fall
Weather Variable (695) (2317) (1635)
Wind speed 7.175* 0.5058 32.58**
Temperature 2.589 3.172 20.33**
Barometric pressure 2.796 0.6055 50.99**
Light intensity 0.9359 4.206 42.39**
Cloud caver 2.485 1.140 9.028**
Precipitation intensity 1. 593 13.17** 1. 407
Day of year 57.25**
Humidity 0.9603
Insect harassment o. 9119
40
because of small or zero sample sizes ~n spring and fall), and
moderate levels of precipitation. It should be noted that sample
sizes for periods of precipitation were small; in rainy weather I
generally could not see the study sites. Clear patterns of change in
activity levels were not apparent in relation to temperature or
barometric pressure. Day of year, which was included with weather
factors in summer because the summer study period was much longer
than spring or fall, provided the best separation between active and
inactive moose (Table 2). Moose were less active as the summer
progressed. Correlations among weather factors showed a diurnal
pattern similar to spring, and also a seasonal pattern (Appendix
8b).
In fall, significant differences existed in activity levels of
moose in relation to all weather factors (Fig. 7, Table 2) except
precipitation intensity which, as in summer, was represented by small
sample sizes. High levels of activity were associated with low wind
speed, northerly winds, low temperatures, high cloud cover, and low
barometric pressure. Results are more difficult to interpret,
because correlations among weather factors were weaker than in spring
and summer, and did not show a clear diurnal pattern (Appendix 8c).
I believe this is because weather conditions were very different in
the fall durinf th~ two years of the study; in 1976 weather tended to
be clear and dry, with cold nights and warm days, while 1977 was
cloudy and wet with little temperature fluctuation (Fig. 3a-b).
Moose were less active at high wind speeds, high temperatures, and
r
41
high light intensity, and at high barometric pressures. This pattern
of correlations corresponds in part with diurnal and seasonal changes
~n activity I noted during the two years: activity tended to be
highly crepuscular in fall (Fig. 4f-g), when light levels,
temperatures, and wind speeds were law. However, activity also
appeared to be less intense in fall of 1977, when many law pressure
systems moved through the Park.
No significant correlation was found between rate of change of
barometric pressure and activity levels throughout the study period
(r=0.231, n=19, p>O.OS).
Differences in activity levels of moose in different sex-age
categories under different weather conditions were also highly
variable; these differences were usually statistically highly
significant, but seldom showed a clear pattern of activity
differences among different sex-age categories (Fig. 8, Appendix 7).
Such was the case with activity levels with changes in light
intensity, cloud caver, precipitation intensity, and wind speed.
However, clear patterns of sex-age differences in activity were
seen with sorne weather factors (Fig. 8). In terms of the chi-square
analyses, bath bulls and cows were more active than expected when
winds were northerly or easterly, and cows with calves were more
active when winds were southerly in spring, summer, and fall. In
summer and fall, bulls remained active at higher temperatures than
cows with or without calves, although all sex-age categories tended
to be most active at law to moderate temperatures. Bulls were also
Spri ng
a.
en en
0
u
Q)
01 b. <t
1 :~f '\ )(
Q) en •• .s::
(,) 1 . . \ 0 1 . w 40~47 c: 1 ' .
. ''\.95
Q)
20 J \a3 en
0
0 1 7·14 0
:E 1 1
0~ 15·22
Q)
> c. -80 (,)
<t -60 0
en c: 40 0 -0 20 > ...
Q)
0 en
J:) -10·-5 -5-0 0-5
0 d.
0 80~ -~
60 -0 -40 c:
Q)
(,) 20~ ...
Q) a.. t.· ......
0 0·9
Spring
**
/
Summer
N
w E W
s
Wind Direction
--Bulls
.,--Cows w/o Co Ives
-·-·-Cows w/Colves
....
.•. /\.
; ',~.
',v'-
Fa li
N
•o~ @'~-~-... -E
~?R3~ l' 178
175/
s
15·22 23-30 31+
.. ..
242 4;;;-.,, 1531
1 1 't-., 1306 ...._-+1--+1--+1 --"
-10·-5 -5·0 0·5 5·10 10·15 15·20 20-25 25·30 -10·-5 -5·0 0-5 5·10 10·15
72
f118
1
1
1
8)·100
Temperature (°C)
0-9 10·19 20-39 40·59 60·79 80·100
Cloud Caver (%)
Summer
::::.----
46
/239
1
.____,,...__-·.;;.'··-" 1 1
0·9 10·19 20·3940-'59 60·79 80·100
Fall
42
Fisure 8. Activity of bulls, covs wit:-wut calves, and cm-;s t-lith calves
unèer various weather conC:itions, ::!enali ~rational Park, 1976--77.
Sanple sizes are indicateë near each gra?h. Results of chi
square analysis testing inciepenè.=nce of nunber of active versus
inactive moose in each sex-a[;e category and v7eather are indicated
where significant (*p < ~.01, **p < 0.001).
d
'Il
'Il
0
1.)
al
Cl
<l
1
>C
al
(/)
~
(.)
0
u.J
c:
al
(/)
8
:E
al
> -(.)
<t -0
(/)
c: . 2 -0 > ...
al
(/)
.Q
0
0
~ -0
~ 0
e. Spring Summer Fa li
100
80 .. .....
60 ·" 40
20 -~~~to
0~ ~~'.1 ,--"\
:/" 242
3·12
o-.75.75·3-+--..._ .50~-200
12·50 0·.75
f.
g .
60
40
20
...
3·12 12·50
....
>200 o-.75 3-12 12·50 >2oo
60
40
20
Li g h t l n t e n s i t y ( 1 1m2 )
**
0 ·-
0
--Bulls
----Cows w/o Ca ives
·• -· -Cows w/Calves
.. ...
' ~ 1/ . \ \~---116 ,. ... ., . \ " 242
\ ~ . \ '"
\ 64 6/·;_:6 ~
·,_ _______ 97 (/.7 ~ 961 1 \ .:::e:-=--'--'~220
0 1 735:740 745·750 4 ·745 755·760 ·'!>354 l ·• \ ..,;......__+-_ • 1 1 1 1 T l 1 ,_ .. _._.-_1 1 1
<735 740·745 750·755 ~735735·740 750·755 760·765 <734 740·745 1 750·755 760·765
735·740 745·750 755-760
(mm Hg)
Spring Summer Fa li
43
Figure 8. Activity of bulls, cows without calves, and cows with calves
under various weather conditions, Denali National Park, 1976-77.
Sample sizes are indicated near each graph. Results of chi
square analysis testing independence of number of active versus
inactive moose in each sex-age category and weather are indicated
where significant (*p < 0.01, ** p < 0.001).
44
more active than cows when humidity was high in summer. A higher
proportion of bulls than cows tended to be active at high barometric
pressures.
Habitat Use and Weather
Moose showed differential habitat use in different weather
conditions (Tables 3-4) throughout the study period. In spring,
moose used short open and forest habitat types at lower temperatures
and light intensities than tall shrub. In summer, moose used short
open habitats when wind speed, temperature, and light levels were
low, and cloud cover, precipitation intensity, and humidity were
high. In fall, moose used short open habitats when wind speed,
temperature, barometric pressure, and cloud cover were low.
DISCUSSION
The intent of the present study w~s to determine what variation
' in weather conditions influences moose behavior. The response of
moose to virtually all weather conditions measured was statistically
significant in one or more seasons; however, I think there is good
reason to doubt that statistical significance is an accurate
reflection of biological significance in all these instances.
Results of other studies of moose have been ambiguous. It appears
that moose do respond to changing weather conditions with altered
activity or habitat use, but these responses are not as strong nor as
li M ' • • • • • •'" '"" ••w -•·--····· ,..
_..-,
Tabl<•]. Heans "'"' slaol<lard devlallons of W<'alhn faCLors for acotve and '"'""live moo,;p ln vadmos hahtoao lvi'""• llPnall N.ollnu<OI l'ark, I'Jif.-77,
FIRurt•s in JMl"Pnlh(•tu~s are m('an vahws for orcllnal v;Hiithle.s. t'-st.lt l:>ll<·n rnr thos{• clat a ;1rl' Rlvc•n ln Tablf~ 4.
Act lvP
lnac·tl ve
W<'<tiiH•r fn•·tor Short Opt•n Tall Shrub Jo'orc•st Short Opr•tt Tati Slu-uh Forest
Sp 1 ~ '~t;
( 1. 71) W i nd S(lC('d 1 nd l'x ( 1. 1~) 1. 14 ( 1. 67) Il. q) 0.97 (1.71) 1.n ( 1. H<J) o. /47 ( 1. Il) I.OH
Tt·rnperature 7.1 2. ~ 9.1 2. 79 7.1 1.1 6.f. 2. 5 R.9 2. ~ 1.1, 1.4
Ranmwtric
l'ressttrP 77~. 1 4.0 771.2 4. 5 778.1) ~. 6 7 74.4 4. 1) 175. b 7.1 7/f.. 1 '. 2
l.t~ht lnteu~lty 1199.51 ' Rl9 .65 1641. ~~ • 900.40 1~2].29 1 Rlcl. 22 151\2.99 ' 9JR.oo 15o7. 84 1105.95 1166. 7H 1 ]i.J. J 1 Cltuul c,,ver '•-96 1. 57 4' 72 1. 79 4. 55 1.% 4. (12 1. 77 4. 17 1. 9J 4. lh 2.01
l'rf't·lpl t .1t ion
lntt•nr-;lty lndPx (0. 11>4) . o. 741 (0.087) ' o. 284 (0. 290) ' o. 710 (Il. 195) ' Il. 594 (Il. 115'1) Il. 2 IH (O. 14fo) ' o. f./9 Sumuu.•r
W 1 nrl Spt'f'd lrhh.•x ( 1. 41) 1' Il ( 1. 85) 1. 11 ( 1. RJ) 1. 16 ( 1.4 J) 1. 21 ( 1. bH) 1.19 (2.11/,) 1.119 Tt>IIIJH'fntut c Il. JI 4. 17 tt,,t,o 4.o) 1].)1 J. IR 1 1. Ill ~-11 ·-11t. 50 4 .• 1 14. ~5 2. Hfl
Ua romPt rte
l'rt•SSUTf' /HO. 4 5. 4 /Hl. 1 5. 2 781.9 4 ·'• 780.7 6.4 /RI.() 5.7 7HI. H 5. 4 1.1 ghl lut ''Il~ 1 t y 508. 54 ' 86.74 9J 7. Ill ' o/4. 48 9foq. 61 • flll.n olt. 211 1 1 'ill.l9 919. 9R ' ,, 11' 24 992. 9H ')')H.lH l:lo•ul c:ovcr 4. )qb 1. 616 4. 12 1. 89 4. 65 1.(,9 4. Ho 1. IR 4.45 1. 9 7 4. 9 1 1. 12 Pt f't·lpltat lon
lut<>IW 1 t y J nd ex (0.1 ~2) ' 0.4)1 (Il. 1 15) O. 448 (O.IRH) . o. 544 (11.104) . o. 190 ( ll.f) Il) ' O. IHO (II.OfoR) o. 279 lltunJd 1 t y 62.0 ''"0 ~ 1.() IJ.O 60.0 ll.O 61.0 IH.o Sfl.O 14.0 60.0 9. 0
lnspt·t
liat assmPnt ltlllf'X (0. 7Hio) ' Il. 814 (Il. 712) . O. 716 (0. 725) ' 0.61JO (O. 5H9) ' n. 7'd (0. 859) ' 1. 01 (O.Vd) O.hO'I
llay t•f V(•ar 20{). 7 22.2 198' 8 23.9 I9H. 5 ' 24. ~ 21ft. 1 l2. 7 2114. 5 21.0 w:. 9 ' 22./ Fa Il
W 1 n~l Spt•(•d 1 n<IC'x ( 1 .40) 1.16 ( 1.1>9) 1. Il ( 1. loi) 1.11 ( 1. 51) l.tf. ( 2 .09) O.H26 (l. co)) 1.7'• l'~'mpt·raturp 0,972 'l.OtJ' 4. 95 l.9l 2. 21 '). )1, l.lil ~. 15 '•-9'1 , .. '14 f.. RH 1. 9/ 1\;trt•un·t rit
l'rt'ssurt• 711>. 2 7. 4 719. 2 '·· 9 1/]. 7 7. 2 liA. H f..O JJH. q 5. ~ llh. 9 (,,, 1.1 f~ht lnl •·us i 1 v 1/5. '){) 1 l'i4. 12 'l08. '•U 1 125. 'H '·00.')7 1 I')H.hl, 57H, RI 1 '•.lf•.'•R )fllt, r)(} 2H2. ]'i '"'1. li 14H. 11 Cloud Cnvt•r 4. )lt 2. 1 1 t,,lfl 1. 91 4. 95 1. ')') L 117 2.01 , •. :n I.HO 'l.IIO 'l. 'l_lt l'rt•t·l p Il al Inn
(O.'Jtn) ILitHl (O.(, U•) n. l7H
lult•ns Il y IIHif"x (0.121) ' O.'iH5 (0.241) ' n.hl'• (11.221) ' O.'iC)(, (Il. 219) 0,') t'
~
Vt
Table 4. F-statistics from analysis separating active and inactive moose in various habitat types on the
basis of weatlter variables, Dena1i National Park, 1976-77. Sample sizes are indlcated in parentheses
(*p < 0.01, **p < 0.001).
Spring (770)
Weather Factor F F Actlvity Habitat F llabxAct
Wind speed 7.1!28* 2.707 o. 259
Temperature 1.041 35.866** 1. 201
Barometric
Pressure 1.362 18.912** 21.687**
Light lntènsity 1. 464 4.71!6* 4.526
Cloud Caver 2.101 2.101 0.851
Precipitation
Intensity 2.966 10.904** 2.282
llumidity
Jnsect lntensity
Day of Year
FActivity
0.661
3.698
0.913
2.425
1. 602
44.016**
0.552
54.449**
Summer (6061)
F llahitat
68.146**
32.017**
FllnhxAct
8. 746**
1.964
15.209 0.849
6.650* 2.326
78.320** 4.743*
5.674* 2.493
57.642** 1.483
2.145 4.036
18.052** 3.610
Fall (1750)
F i . Act v1ty FHabitat FHabxAct
27.557** 17 .224** 29 .102**
7.643* 90.61!6** 13.962**
25. 716** 31.514** 7.316**
38. 341** 3.082 13.520**
4.785 25.031** 10.414**
2.212 2.745 10.13fl**
24.951**
.p.
0\
, .......... ~ ... ·~··~·· .. ···~ .. ~-~.,., •.. ,~···~·····~~-~-~~-····~··-·~
predictable as with seme ether ungulates (e.g. Christie, 1967;
Darling, 1937; Fox, 1978).
47
The effect of wind speed on moose behavior is clear; moose in
this study showed reduced activity or use of denser habitat types or
beth in high winds. In ether studies as well, moose have been
observed to reduce their activity (Joyal and Scherrer, 1978;
Glushkov, 1976) or avoid open areas (Peterson, 1955) or beth (Skunke,
cited in DeVos, 1958) in windy weather. This behavior has been
attributed to the greater difficulty in detecting scents and hearing
in windy weather (Skunke, cited in DeVos, 1958). In the present
study, activity levels remained high in the summer except at the
highest wind speeds (Fig. 7), but use of tall dense habitats was
associated with high wind speeds. This suggests moose remained
active, but moved into denser cover to feed. Moderately windy
weather in summer may alleviate insect harassment, which might also
~
be a factor in activity levels remaining high.
Response to temperature is less clear. In this study, moose
tended to be more active at high temperatures in spring, but less
active in fall, with no clear pattern in summer. DeVos (1958) and
Geist (1963) found no difference in the number of moose they observed
on warm or cool days; in contrast, feeding by moose has been
negatively correlated with temperature in some summer studies
(Belovsky and Jordan, 1978; McMillan, 1954). Habitat use varied
consistently throughout the study period, with moose tending to use
short open habitat types at low temperatures and taller, denser
habitat types at high temperatures; this may well be part of the
diurnal pattern of habitat use (Fig. 6) rather than a response to
temperature per ~·
48
Responses to cloud cover, precipitation, and humidity are not
clear. Activity levels tended to be highest in partly cloudy weather
in spring, clear weather in summer, and mostly cloudy weather in fall
(Fig. 7) in the present study. Activity also tended to be greater
when precipitation was present. Most othe~ observers, in contrast,
have noticed higher activity levels in clear weather (Mould, 1977;
Joyal and Scherrer, 1978) and reduced activity in rain (Markgren,
1966; Skunke, cited in DeVos, 1958; Joyal and Scherrer, 1978). There
was a clear bias in this study toward periods of light precipitation
when visibility remained high, so what I observed during periods of
light precipitation may not be representative of times of moderate to
heavy rainfall. It may be that periods of light precipitation, with
their lower light intensities and cooler temperatures, are used by
moose to extend activity periods. Mean cloud cover values tended to
be highest for moose observed in short open habitats (Table 3),
suggesting that clouds are performing a shading function performed by
vegetation in tall shrub or forest habitat types.
The stimulating effect of clear weather on ungulate rutting
behavior has been described by.Fraser (1968). Rykovskii (1965) noted
bull moose stopped calling in rainy weather, and rutting behavior was
less intense when weather was warm or cloudy. Roby (1978) and
Curatolo (1975) both reported a negative correlation between cloud
r
49
cover and rutting behavior in caribou. I observed the same pattern
of behavior in the present study; activity levels in relation to
temperature and light intensity support my subjective impression, but
those in relation to barometric pressure and cloud cover do not
(Fig. 7).
Barometric pressure appeared to be an important factor in
relation to moose behavior in the fall, but not summer,-and only in
relation to habitat use in spring (Fig. 7, Tables 2-4). Evidence
from studies of several other mammals has suggested that brown bears
(Craighead and Craighead, 1972), Dall sheep (Heimer, 1973), and
caribou (Henshaw, 1968) may be able to detect and respond to changes
in barometric pressure. No differences in moose activity with
changing barometric pressure have been detected in previous studies,
however (Glushkov, 1976; Geist, 1963). There was no correlation
between rate of change of barometric pressure and moose activity, but
a strong relationship between absolute barometric pressure and
activity, which I am unable to explain.
Sex-age differences in activity, even when consistent, seem
inexplicable, and I tend to doubt their validity. Bulls remaining
active at higher temperatures and humidities than cows may be
evidence for somewhat different physiological mechanisms at work ~n
the two sexes; possibly bulls are able to dissipate heat from their
antlers prior to shedding of velvet. Without further evidence,
however, I am more inclined to attribute the results to sampling
artifacts, rather than true behavioral differences.
IMPLICATIONS FOR MANAGEMENT
50
Variability in moose activity and habitat use in different
weather conditions limits predictability for aerial survey purposes.
It appears that once diurnal patterns of change in weather conditions
are taken into account, other weather conditions tested probably
played a relatively minor role in directly and immediately
influencing moose behavior in this study.
The exception is moose activity and behavior ~n relation to wind
speed. When winds were strong, moose were less active and/or used
taller, denser habitat types than when tbere was little wind. Either
behavior would make them more difficult to observe during an aerial
survey. Aerial surveys are not normally conducted in very windy
weatber because of viewing difficulties associated with pilot and
observer; evidence from the present study indicates moose behavior
will lead to a further underestimation if surveys are conducted in
these conditions.
Applicability of the resulta of this study to other areas is
limited because of the absence of clearly delineated changes in
behavior. In areas where changes in weather are more clearly
defined, such as Soutbeast Alaska, it might be important to consider
weather conditions for their influence on moose behavior. However,
~n this study, I would say weather is important primarily for its
influence on pilot and observer, and not for its influence on moose.
51
SECTION IV
CHARACTERISTICS OF AGGREGATIONS
RESULTS
Seasonal and Sex-Age Differences in Aggregation Size
Mean aggregation size increased through the year. Mean
aggregation size was 1.0 (SD=O, n=14) in late winter, 1.1 (SD=0.91,
n=59) in spring, 1.5 (SD=1.6, n=404) 1n summer, and 3.3 (SD=3.3,
n=101) in fall. As mean aggregation size increased seasonally, the
proportion of single animals observed declined (Fig. 9).
Aggregation size was influenced by sex-age composition.
Aggregations of bulls only and cows without calves only were similar
in size in spring and summer (Table 5), but the cow without calf
groups were much larger in fall. Mean size of mixed groups was much
larger than bull or cow without calf group size throughout spring,
summer, and fall. Differences in group sizes by sex-age category
2 were not significant in spring, but were in summer (X =99.418, df=4,
p<0.001) and fall (X 2=49.023, df=4, p<0.001). Cows with calves were
rarely seen in association with other moose, and their mean group
size did not change seasonally.
Aggregation Size in Relation to Habitat Use
There was a strong interrelationship between aggregation size
and location in spring (X 2 =78.01, df=6, p<0.001), summer (X2=237.73,
df=14, p<0.001), and fall (x2=191.22, df=l6, p<0.001). In spring,
52
100
"'0 80
<l)
> .....
<l)
fi)
.0
0 60
fi)
Q.
::3
0 .....
(!)
-40
0
~ 0
20
SPRING
53
Q L 1 ' ' r 1 1
2 >2
SUMMER
,......, 322
r--
.--
2 >2
Group Size
r--
FALL
89
r--
r--
2 >2
Figure 9. Group sizes of moose, Denali Na~ional Park, 1976-77. The
number of groups observed in each season is indicated.
53
Table 5. Mean sizes and standard deviations of bull and cow without
calf aggregations in Denali National Park, 1976-77. The
number of groups observed in each season is indicated in
parentheses.
Spring
Summer
Fall
Bulls Only
1.33 ± 0.58 (3)
1.54 ± 1.00 (6)
1.13 ± 0.34 (16)
Mixed
4.00 ± 2.83 (2)
4.11 ± 1. 77 (52)
5.56 ± 4.93 (39)
Cows Only
1.28 ± 0.74 (25)
1.58 ± 1.33 (113)
3.61 ± 3.84 (26)
54
groups of one or two moose were observed in tall dense habitat types
(tall shrub and forest) more than expected. Groups of three or more,
however, were observed more than expected in short open habitats.
The same pattern was observed in summer, except in the case of large
groups of six or more moose; they were observed most often in tall
shrub or forest. In fall, smaller groups (~5) again preferred tall
dense habitat types, and large groups preferred short open habitats.
Synchrony of Activity within Aggregations
A high degree of synchrony of activity occurred among moose
within aggregations (Table 6). Synchrony, when all moose in an
aggregation were either standing or lying, occurred in 97, 83, and
57% of groups observed in spring, summer, and fall, respectively.
Aggregations showed a higher level of activity than single
moose, spending more time active or partially active, and less time
inactive, than sing:2 animals (Table 6).
Weather and Aggregation Size
No relationship between weather and aggregation size was
identified. Precipitation intensity best explained differences in
aggregation size in spring (Appendix 10), accounting for 18% of the
variation. In summer and fall, the best variables exp1ained on1y 1
and 2%, respectively, of the variation in aggregation size. Wind
direction, considered separately, had no significant impact on group
size.
55
56
Table 6. Synchrony of activity of aggregated versus single moose,
Denali National Park, 1976-77. The number of observations is
indicated in parentheses.
Group
Size
Spring 1
>2
Summer 1
;: 2
Fall 1
>2
All Inactive
70% (120)
46% (17)
34% (152)
17% (26)
9% (2)
20% (20)
Part Active
3% (1)
17% (26)
43% (43)
All active
30% (52)
51% (19)
66% (299)
66% (102)
91% (20)
38% (38) 1
l !
t
1 t
1
1
i
1 f
1
:
j
'
î
l
1_
57
DISCUSSION
Social groups of a temporary nature have long been noted to
exist among moose, despite their solitary nature compared with other
cervids (e.g. Peterson, 1955). These groups vary in size; the
variation is related to "breeding activities, mother-young relations,
m~le social system, sex ratio of the population, and external
influences of forage, topography, and cover" (Peek et al., 1974; p.
135).
Although moose commonly occurred in aggregations of two or more,
most groups contained one animal (or cow with calf). I observed
about the same proportion of lone moose and a higher proportion of
groups consisting of more than two moose as in other studies (Table
7).
Seasonal and Sex-Age Differences in Aggregation Size
Seasonal patterns of aggregation size vary greatly among
populations. On the Kenai Peninsula, seasonal patterns of aggregation
size were similar to what I observed in Denali National Park (Peek et
al., 1974). Mean aggregation sizes were small in late winter,
somewhat larger in summer, and increased through the rut to the
largest values in late October on the Kenai Peninsula. Great
variability in gruup size there in spring also suggested a tendency
for moose to be aggregated then, although mean group sizes were still
small. While I did not observe these large spring aggregations when
I began field work 12 May, other researchers in the Park have noticed
Table 7. Frequencies of group sizes observed in the present study and
other moose aggregation studies. Sample sizes are included
in parentheses whenever possible, as well as the portion of
year included in the study period.
Group Size
1 2 >2
Houston (1973) 58% 26% 16%
(Jan-Dec, 3249)
58
Geist (1963) -60-85% -10-30% -3-15%
(May-Sep)
Dzieciolowski (1979) 48% 33% 19%
(Jan-Dec, 345)
Present study 62% 13% 25%
(:t-'lay-Nov, 595)
t
t
1
1
i
them earlier in the month (VanBallenberghe, pers. commun.) In other
studies, moose have shawn different seasonal agggregation patterns.
Berg and Phillips (1972) observeâ the smallest groups in Harch and
April and the largest in October, as I did in the present study, but
aggregations continued to be very small in summer in Hinnesota,
whereas I found aggregations larger then than in late winter, based
on a small late winter sample size. Group sizes in sorne other
populations have been largest in winter and smallest in summer, with
intermediate values in spring and fall (Geist, 1963; Peek et. al,
1974). In all studies, aggregation sizes tended to be largest in
late fall or early winter. In other seasons, the tendency to
aggregate is highly dependent on characteristics of a given
population.
Sex-age category of moose is also a factor in aggregation size.
Cows with calves were seldom observed associated with other moose in
the present study; the same pattern of avoidance of other moose has
been observed elsewhere (e.g. Houston, 1974) and has been attributed
to the cow's defense of the calf against any abject construed as
threatening (Geist, 1963). Bulls and cows without calves were more
sociable and were commonly observed in association with other moose.
Group sizes of cows without calves, which reached maximum size in
fall, approximated those observed on the Kenai Peninsula. Peek et
al. (1974) postulated that large cow groups there were a consequence
of a lower bull:cow ratio there than in other areas in that study.
(
The bull:cow ratio in Denali National Park, estimated at 31 to 45
59
60
bulls per 100 cows during this study (Troyer, 1980), ~s also lower
than in seme ether studies (e.g. Peek et al., 1974). In addition,
calf survival was extremely low during the study (Troyer, 1980); as a
result, there was a high proportion of cows without calves on the
study area by early summer. Bulls, too, were commonly observed in
association with ether bulls or in mixed-sex groups. Studies in
Alaska (Peek et. al, 1974), Ontario (Cobus, 1972) and Montana
(Knowlton, 1960) have also reported bull associations are common. In
ether studies (Altmann, 1959; Geist, 1963), however, bulls were
solitary in summer.
Aggregation Size in Relation to Habitat
Moose (Peek et al., 1974) and ether ungulates (e.g. Hirth, 1977)
tend to form larger aggregations in open habitats. I observed this
pattern of behavior in spring, and in summer for small and
moderate-sized groups. The use of dense cover by very large groups
in summer in the Park is not easily explicable; it may be a
consequence of a large number of moose concentrating in a small area
of excellent habitat, and aggregating because of proximity. The
large aggregations that formed in the fall moved into open shrub or
tundra portions of the study area as a part of reproductive
activities (Lent, 1974).
Crook (1970) suggested that larger group s~zes in open habitats
have a psychological basis, that the greater number of group members
in these habitats is a substitute for cover provided by vegetation in
61
denser habitats. Invoking such a hypothesis for large group sizes of
moose in open areas in fall does not seem necessary, but it may
provide the best explanation for the same tendency at ether times of
the year. Smaller group sizes in dense cover may also be a
consequence of the difficulty of visual communication between animals
in those habitat types.
Synchrony within Aggregations
The degree of synchrony of activity of moose within an
aggregation influences sightability of moose during aerial surveys.
Because a lying moose is more difficult to see than a standing one,
aggregations with one or more moose standing will be easier to detect
than one in which all moose are bedded.
Results indicate tnat moose within an aggregation do in fact
tend to synchronize their activity with other group members. Gasaway
et al. (1980) observed a high level.of synchrony within moose
aggregations; furthermore, this synchrony expressed itself in a
generally higher level of activity within aggregations than among
single moose. Of the aggregations they observed, 88% showed
synchronous activity and 60% of those were standing groups. In the
present study, 97%, 83%, and 57% of aggregations observed in spring,
summer, and fall, respectively, showed synchronous activity (Table
6). In one half to three quarters of these groups, all moose were
standing. The proportion of aggregations with all animals lying was
much lower than for single moose throughout the spring and summer.
i
J
This suggests, as Gasaway et al. (1980) observed, that the amount of
time spent active is greater when a moose is associated with other
moose. From spring through fall, there was a decline in the degree
of synchrony observed. I believe this is because mean group sizes
were increasing through this period (Fig. 10). This increase in
group size, especially in fall, made it increasingly likely that one
or more moose would remain feeding after the first bedded clown.
Bedding clown or resumption of activity by the entire group was often
spread out over an hour or more within very large groups.
Weather and Aggregation Size
Weather does not appear to influence aggregation size of moose.
Because moose form very temporary aggregations, the potential exists
for them to respond to short term changes in weather conditions with
altered aggregation s1zes. This was not the case in the present
study, despite ether changes in moose behavior with changing weather
(Section III).
IMPLICATIONS FOR MANAGEMENT
Aggregation behavior of moose has a potentially great effect on
results of aerial surveys. Moose in aggregations have a greater
chance of being observed on aerial surveys than lone moose because
aggregated moose show a high degree of synchrony of activity and an
increased level of activity. To achieve an accurate total count of
moose, therefore, surveys should be conducted when moose are the most
62
63
aggregated--in late fall and early winter. Most moose surveys Ln
interior Alaska are conducted in early winter, as soon as snow cover
is complete. Smaller aggregations during the remainder of the year
will make it more difficult to assess total numbers of moose.
Sex-age differences in aggregation sizes suggest that biased
composition estimates will result whenever surveys are conducted.
Cows with calves will be underestimated because of their isolation
from the larger and more easily seen aggregations.
Mixed-sex aggregations have the largest mean size Ln sprLng,
summer, and fall, which will tend to reduce the bias toward either
bulls or cows without calves. Cows without calves will be easier to
see in the fall, because of their large mean aggregation size, but
this may be offset by the high visibility of bull moose antlers when
velvet has been shed.
1
!
J
SUHMARY AND CONCLUSIONS
Season appeared to be the most important influence on diurnal
activity patter.ns in this study. Activity showed the least variation
through the day in mid-and late summer, and showed the largest peaks
and troughs during pre-rut. Sizable peaks in activity levels,
suitable for aerial surveys, occurred twice a day during
pre-calving/calving, and in the afternoon during rut. Throughout the
study period, activity levels were lowest in late morning, and survey
work should be avoided at that time. Predictable composition biases
will not occur on the basis of activity alone.
Habitat use and activity were interrelated; moose tended to use
more open areas for feeding and move into denser cover for bedding.
This means that inactive moose will be extremely difficult to see
during surveys, and emphasizes the importance of conducting surveys
during diurnal activity peaks to achieve as accurate a count as
possible. Bias in composition counts will occur whenever surveys are
flown as a result of differential habitat use by various sex-age
classes. Cows with calves will tend to be underrepresented because
of their greater use of tall shrub habitat types; bulls will also
tend to be underrepresented in spring and summer because of their
greater use of forest. Fall is the best time for aerial survey work
because all sex-age classes use open habitat types more than in
spring or summer.
Weather did not appear to be as strongly interrelated wih
64
..........
65
activity and habitat use. Moose were less active or were in taller,
denser habitats when winds were strong. Otherwise, most significant
changes in activity or habitat use with changing weather conditions
appeared to be part of a diurnal pattern, and can be most effectively
considered by considering those diurnal activity patterns ~n
themselves.
Aggregation characteristics play an important role in aerial
visibility of moose. Mean aggregation sizes increased from late
winter through fall, and varied by sex-age category. Composition
bias will result from the isolation of cows without calves from other
moose. Moose in an aggregation showed a high degree of synchrony of
activity and spent more time active than single moose; the latter
behavior pattern will make moose in an aggregation easier to spot
from an aircraft. Aggregation size and habitat use were
interrelated; aggregations tended to be larger in open habitat types,
but aggregation size appeared to be unrelated to weather.
Fall is the season when most aerial surveys are conducted at the
present time. Findings in the present study confirm that this is the
optimum time for conducting such surveys because moose spend more
time in open habitats and are more aggregated than at other times of
the year. Since surveys cannot be conducted around dawn and dusk,
when activity levels are at a maximum, they should be conducted in
the afternoon when activity is fairly high. Activity levels of moose
are very low in late morning in the fall.
The importance of doing replicate censuses must be emphasized •
Because diurnal activity patterns changed so rapidly over fairly
short periods of time, they might be expected to vary at the same
time from year to year, depending on phenology. Repeated censuses
will permit the calculation of means and variances.
66
.....t
LITERATURE CITED
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67
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68
Darling, F. Frazer. 1937. A herd of red deer. Oxford Univ. Press,
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...........
69
Henshaw, J. 1968. The activities of the wintering caribou in north-
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Krefting, L. W. 1974. Moose distribution and habitat selection in
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area, Alaska.
Movement patterns of moose in the Calville River
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_t
71
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(
PERSONAL COMMUNICATION
William C. Gasaway, Alaska Department of Fish and Game, Fairbanks, Alaska
Victor VanBallenberghe, Institute of Northern Forestry, University of
Alaska, Fairbanks, Alaska
72
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......
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74
Appendix 2. Three-way chi-square analysis of habitat use, activity, and
sex-age class of moose, Denali National Park, 1976-77
(**p < 0.001).
x2 (df)
H Spring 0 Summer Fall
Habitat use, activity, 325.480(12)** 105.010(12)** 151.597(12**)
and sex-age class are
mutually independent
Habitat use is indepen-253.538(10)** 81. 908 (10) ** 143.802(10)**
dent of activity and
sex-age class
Activity is independent 319.255(10)** 87,655 (10) ·H 23.136(10)
of habitat and sex-age
class
Sex-age class is inde-170.898(8)** 69.692(8)** 144.525(8)**
pendent of activity
and habitat use
75
Appendix 3. Two-way chi-square analysis testing the hypothesis habitat
use is independent of activity among bull, cow, and cow
with calf moose in Denali National Park, 1976-77 (*p < 0.01,
**p < 0.001).
Spring
Bulls 27.365(2)**
Cows without calves 6.141(2)
Cows with calves 32.783(2)**
x2 Cdf)
Summer
30.681(2)
0.958(2)
9.651(2)*
Fall
62.769(2)**
71.322 (2) **
5.109(2)
76
Appendix 4. Three-way chi-square analysis of time of day moose were
seen, habitat use, and sex-age class in Denali National
Park, 1976-77 (**p < 0.001).
Ho Spring Summer Fall
Time, habitat use, 373.389(28)** 268.196(36)** 575.222(28)**
and sex-age class
are mutually inde-
pendent
Time is independent 215.375(24)** 231.956 (32) ** 477.309(24)**
of habitat use and
sex-age class
Habitat use is inde-223.618(22)** 252.496(28)** 436.896(22)**
pendent of time and
sex-age class
Sex-age class is 246.910(22)** 134.178(28)** 234.728(22)**
independent of hab-
itat use and time
1
...........
77
Appendix 5. Two-way chi-square analysis testing the hypothesis
Bulls
Cows with-
out calves
Cows with
calves
habitat use by moose is independent of time of day among
bulls, cows without calves, and cows with calves in Denali
National Park, 1976.-77 (**p < 0. 001).
x2 (df)
La te
Spring Summer Fall Winter 1
88.092(18)** 196.622(38)** 59.517(26)**
69.906(30)** 270.584(38)** 105.850(26)** 6.532(8)
68.408(30)** 71.447(30)** 32.395(6)**
1All sex-age classes combined .
78
Appenàix 6. Two-way chi-square analysis testing the hypothesis
moose activity is independent of weather for specified
weather variables in Denali National Park, 1976-77
(*p < 0.01, **p < 0.001).
x2(df)
Weather Variable Spring Summer Fall
Wind speed 6.687(3) 36.751(4)** 33.748(4)**
Wind direction 8.993(5) 205.877 (7) ** 60.357(6)**
Temperature 18.371(3)** 20.015(5)* 46.459(4)**
Barometric pressure 10.137(3) 39. 720(5) 55.395(5)**
Light intensity 2.733(3) 35.995(4)** 60.342(4)**
Cloud cover 7.994(5) 66.532(5)** 19.073(3)**
Precipitation intensity 8.716(2) 107.762(2)** 20.373(2)**
Humidity 78.077(5)**
1
\
1
......
79
Appendix 7. Two-way chi-square analysis testing the hypothesis that
the number of active bulls, cows without calves, and cows
with calves observed is independent of weather for
specified weather variables in Denali National Park,
1976-77 (*p < 0;01, **p < 0.001).
x2(df)
Weather Variable Spring Summ.er Fall
Wind speed 28.486(4)** 17.572(8) 17.902(8)
Wind direction 72. 085 ( 4) ** 153.816(14)** 37.647(10)**
Temperature 54.861(6)** 70.586(10)** 61.138(8)**
Barometric pressure 44.641(6)** 52.826(10)** 106.208(10)**
Light intensity 25.225(6)** 29.455(10)* 28.325(8)**
Cloud caver 91.214(10)** 22.307(10) 10.537(8)
Precipitation intensity 32.458(4)** 1.467(4) 6.433(4)
Appendix Ha. Correlation coefficients among weather variables in spring, Dena1i National Park, 1977
(n=395) (*p < 0.01, **p < 0.001).
Wind Barometric Li ght Cloud Precipitation
Speëd Temperature Pressure Intensity Cover lntensity
-----~---~~~----·---~~-~~~~~~------------------------·--------------~~--------------~-~--------
Wind
Speed
Temper~ture 0.4163**
Barometric
Pressure -0.1193 -0.4088**
Light
Intensity 0.3025** 0.4499** -0.0072
Cloud
Co ver o. 224.l** 0.151l3* -0.2507** 0.0735
Precipitation
ln tens ity 0.1667* -0.0411 0.0241 -0.1609 0.2556**
Time of Day 0.2675** 0.4099** -0. 2938** -0.0910 o. 3057** 0.1276
CXl
0
/\ppt'IHII x Ah. Correlation coefficients amnng wt-alher vartahles fn SIIRIIRPI, )}t_•nal f Nat. Jona) l'ark, 197f.-77 (n=R90) (*p < 0.01, Hp < 0.()()1).
-----------------------------------------------------
Wlnd Rarometrlc ).) p,h t C]oud Precipitation IJay of
SpPed Tl•mperature Pressurt> lntensJty <:over 1 nt ens 1 t y llumldlty Y ear
----------------------·-------.---------------------------------------------------------·-------------------------------
Wlnd
SpeeJ
Tl•mper at ure O. l89R**
HaromPtrlc
P rt•ssur e 0.11171** 0.2)25**
J.(ghl
l11l ens 1 t y 0.4)59** o.427R** o. 2209**
Cloud
Co ver 0.074R -0. 1000* -0.1590** -0.071.7
l'recipltation
fllli'IIS fly -0. 20)4** -0.2214** 0.0189 -0.2028** 0.1921**
lhunld J l y -0.4057** -0. 6408** -0.0761 -0.4283** o.t.6l9•• o. ns1••
' .•
Oay nf Year -0.2607** Il. 001 R -0. 1589** -0.48Rl** o.o1 ln 0.05,-l'· O.IMJR**
lnsPct
ll<lf;JSSfllPill -0.1 707** o. 14R6** 0.2415** O. 1974 -(). 2111. 5 ** -0.070 l -0. 1051* -().51 :1]**
Tiuu• of Day 0.0739 o. 1075** -0. )589** -0. 17'•,.)*-A O.OR5l -0.002R -0.1477 O.ORI2
--.------------------------------------------------
IIIS('t'l
IJarclSSJU('UI
0.0559
CIO
l-'
Appendtx He. Correlation coefficients among weather variables in fal1, Denall National Park, 1976-77
(n~523) (*p < 0.01, **p < 0.001).
Wind
Speed
Temperature
Barometric
Pressllre
Llght
lnlensity
Cloud
Co ver
Precipita, lon
lntensity
Time of Day
Wind
Speed
-0.1926**
0.1230*
0.1983**
0.2106**
-0.0443
0.1974**
Temperature
-0. 7881**
-0.1973**
-0.3286**
-0.0916
0.0256
Bnrometric
Pressure
o. 2292**
0.1615**
0.0109
-0.0854
Light
lntensity
-0.2415**
-0.2042**
-0.1973**
Cloud
Caver
Precipitation
lntensity
---~---------~-~------
o. )508**
0.0323 0.0031
CX>
N
Appeudix 9. Three-way
1976-77 0
chi-square analyf'lfi lt_•sttng fndependenc{' of w<•ath<"r fa('lors, actJvlty ;md hahilat
Il : tht" weather factor, actlvlty, and haUltal use R(P mutually lndepenclenl.
Sea~on
Sprlng
Factor
Il
"1
Il
"?
Il o,
Il o,,
~lummf'I Il
"1
Il
"J
Il
"'
Il
o,l
Fall Il
"1
Il
0?
Il
"1
Il o,,
"1
Il : the weather factor ls indPpendent of actlvfty and hahllat use.
0/
Il : .:Jl'l lvlty ls tndepPndent nf wp.1ther and hahltat uSl',
"' Il habitat use ls lndependPnt of weather and activJty.
Ot1
*p . cJ.nl, ••r < o.oo1.
--------. ·----
Wtnd Wlnd J\,1 roml't r tc l.lr,ht
Sp<•ed Ill rection TPmperature Prt·ssurP lntensity
-·-. ----··--------------------~---
65. 758(17)>* 124.475(17)** 141.616(12)** IHI._41H( 17)"* 57.562(17)**
60.509(15)'* 122.289(15)** 111.541(10)** 171l.I<J2(15)** 54.248(15)**
2 50 1110 ( 1 1). 34.141(11)** 20.612(1H)* 79.178(11)** 24.39](11)
61.182(Jl,)** ll8.HR2(14)** 110.45 1(10)** JHI. 585( 14)H 56.109(14)**
lill. 719(27)** 500.,26(37)** 217.325(22)** JHI,.OH9(27)** 24H. 719(17)**
177.1,RL!(25)** 1./1.671(15)** 22'). 512(20)** IHI. )(,2(25)** 21h. J02(15)**
152.1.67(17)** 278.110(21)** (()!1.91,2( l'•l** no. 1H4( Ill"* (,S.OSH(JI)**
)l,R. 606(22)** ~5.617(10)** 221.51/(IR)** 128. P2(22)** 20~.21,0(14)**
427.20J(22)** 216.165(22)** 2,6.1!52(12)** 256.907(12)** 279 .022( 17) ..
315.892(20)** IL,2.901(21l)0 * 129.1195(10)*0 151.156(10)"* 16R.4Hl!( 15)**
2)5.222(14)** 112. 722(1ll)** )l,2.12il(ll)** 111.062(8)"* IRH.92H(II)**
112.195(1H)** IRH.51S(IH)** IHl.IL,',(IIl)** 202. 251!( Ill) •• 16!1.1>57(111)**
Clnml
(:tlVf'f
RI. 306(22)**
71..)11(20)**
24. 861( IL.)
7R.961 (IH)**
162.1H'l(22)**
15~.429(20)**
1 ?1. OOL, ( 1 4) * *
154.059(18)**
229.4"17(22)**
111. 121(20)**
169.821( Il.)**
H>9.HHI ( IH)**
usp of mooHP in Oenali National Park,
Pn·t·ipftat lon lnsect
Jntenslty lhun 1 dl t y llarassmPnt
1
49.4)9(12)**
42.506(10)**
20.HRO(R)*
~6.026( 10)**
104 .97H 12l** 4l7. 929(27)** 271. 719( 17)**
HS. 507( 10)** l.JO. 779(25)** 251!. 092 ( 15) **
75. Hl(!!)** 167 .llO( 17)** 205. 65)(11 )**
'>7. 99H( JO)** "119. H99(22)** )Id. <JI!f, (Il.) H
169.669(12)**
119. 500( 10)**
RJ. 6'JH(H)**
AR.45 1( 10)**
co w
Appendix JO. Regression analyses of wealher variables in relation to aggregation slze i11 Uena1i National Park,
1976-77. Sample slzes for each ana1ysis are indicated in parentheses.
Spring (51) Summer (147) Fall (ll9)
Weather Weather Weather
Variable R? Simple R Variable R? S Impie R Variable R2 Simple R
----~ ~----
Precipitation llarometrlc
Intensity 0.171l02 0.4219'1 Pressure 0.01347 0.11608 Cloud Cover 0.02167 -0.15183
Time of Day 0.20069 -0.12542 Light Tntensity 0.02417 -0.07196 Light Intensity 0.04210 0.11&942
Cloud lleight 0.21537 -0.18515 Cloud Caver 0.03039 -0.09702 Temperature 0.05424 0. 10356
llarometric
Pressure 0.23292 0.06677 Cloud lleight 0.03662 -0.08322 Cloud lleight 0.06]]2 -0.09606
Insect Precipitation
Cloud Cover 0.23646 0.141.48 llarassment 0.04109 -0.04 71,6 1 ntenslty 0.06621 -O.Oil576
T<>mperature 0.23747 -0.13747 Temperature 0.04469 -0.04214 Time of Day 0.06794 (). 06 7 51
Jlaromelric
Wind Speed 0.231l07 0.07970 Time of Uay 0.05256 0.02927 Pt·esfwre 0.061l25 -0.10491
Wind Speed 0.05491 0.01377
Uay of Year 0.05524 0.00737
llumldity 0.05532 0.01908
00
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