HomeMy WebLinkAboutAPA3181CHAPTER VI
PRELIMINARY WATERFOWL DISTURBANCE
STUDIES, MACKENZIE V·ALLEY,
AUGUST, 1972
R. E. SCHWEINSBURG
M.A.GOLLOP
R. A. DAVIS
->
TABLE OF CONTENTS
INTRODUCTION ..•....•...................•...••....•...••....
DESCRIPTION OF SUTDY AREA ....•......•..........••.•••..••..
METHODS
RESULTS AND DISCUSSION .............•.....•...••••.......•..
PAGE
232
233
235
236
REFERENCES CITED . . . . . . • . . . . . . . . . . . . • . . . . . . . . . . • • • • • . • . . . . . . 254
TABLES
1 Species and Numbers of Waterfowl Present on Lake 1,
3-7 August, 1972 .................................. . 237
2 Normal Behavior and Reaction to Aircraft Disturbance
by Waterfowl on Lake 1 ............................ . 240
3 Species and Numbers of Waterfowl Present on Lake 2,
10-14 August, 1972 ..•.•..•. ... .•. .•.•........ ..••.. 242
4
5
FIGURES
1 & 2
3
4
5
6
Normal Behavior and Reaction to Aircraft Disturbance
of Waterfowl on Lake 2 ...•...........•...•.....•.•.
Species and Numbers of Waterfowl Present on Lakes
at Norman Wells, 11 August, 1972 ....••.............
Photograph of typical southern Mackenzie VaLley
Lakes ............................................. .
Photograph of twin otter that utilized lakes at
Norman Wells ...................................... .
Total birds observed on Lake 1 per day, 3-7 August,
19 7 2 .............................................. .
Number of birds observed on Lake 2 (no disturbance).
Number of birds observed on Lake 2 (first day of
disturbance) ...................................... .
xiv
249
252
257
257
238
243
244
TABLE OF CONTENTS continued:
FIGURES continued: PAGE
7 Number of birds observed on Lake 2 (second day of
disturbance) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
8 Number of birds observed on Lake 2 (third day of
disturbance) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
9 Number of birds observed on Lake 2 (fourth day of
disturbance) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
10 Total birds present on Lake 2 at end of daily
observation period, 10-14 August, 1972 ......•....
APPENDICES
1 Physical and Vegetative Features of Lake 1
2 Physical and Vegetative Features of Lake 2
"A" Photos-......... , ....... r. • • • • ~ ••• to .......... (· • -a ............... .
XV
248
255
256
257
INTRODUCTION
The Mackenzie River Valley has been long recognized
as a major waterfowl migration route (Anderson 1913, Cooke
1915, Jones 1956). Until recently, little has been known
concerning productivity of breeding waterfowl in the upper
Mackenzie Valley. Aerial survey data (Davis 1974) have shown
that although much of the Mackenzie River Valley has a low
density of waterfowl, several areas support higher densities.
Lakes are especially important to the many species which breed
there (Figures 1 and 2).
The Mackenzie River Valley represents an important
transportation corridor for materials bound for northern
settlements. Although future northern development will un-
doubtedly mean greater use of the valley by shipping, highway
transport and possibly railway, aircraft will probably con-
tinue to be the most utilized transportation form for some
time to come.
Frequent use of small lakes by light aircraft may have
adverse effects on local waterfowl populations, depending on
the degree of use by aircraft, and the density and composition
of waterfowl species at varying times of year.
Preliminary experiments were conducted on two lakes
in the Mackenzie Valley area to determine the reactions of
waterfowl to repeated aircraft disturbance in late summer.
-232 -
In addition, waterfowl counts were made at the Department of
Transport float base at Norman Wells, which is subject to
heavy air traffic all summer, and on the lake immediately to
the east-southeast, which is on the path of low-flying air-
craft approaching or leaving DOT lake.
DESCRIPTION OF STUDY AREA
LAKE 1
The first study lake was located approximately 25
miles north-northeast of Fort Simpson. Surrounding topography
was flat, with a forest cover of open to scattered stands of
black spruce (Picea mariana) up to 25 feet in height. The
understory was variable but consisted primarily of willow
(Salix spp.), alder (Alnus crispa), dwarf birch (Betula
glandulosa), leather-leaf (Cassiope calyculata) and Ledum spp.
with shrub growth continuing right up to the lakeshore.
Ground cover was mostly moss.
The lake was rectangular in shape, with dimensions of
one mile by~ mile (area .24 sq.mi.), and an average depth of
less than three feet. Beds of emergent vegetation [sedge
(Carex spp.), spike-rush (Eleocharis spp.), bulrush (Scirpus
spp.) and horsetail (Equisetum spp.)], constituted about a third
of the shoreline. Several species of submergents were also
present. A summary of physical and vegetative features is given
in Appendix 1.
-233 -
LAKE 2
The second study lake was located in the Loche River
area, 37 miles east of Norman Wells. The area is characterized
by an abundance of small lakes immediately adjacent to each
other. Forest cover consisted of closed stands of paper birch
(Betula papyrifera) with variable amounts of black spruce and
white spruce (~. glauca). Tree height reached up to 60 feet.
The understory, when present, consisted of willow, with a
ground cover of moss and Ledum spp.
The lake was V-shaped, consisting of two approximately
equal arms~ mile in length (area 0.31 sq.mi.). Average depth
was greater than six feet. Emergent vegetation consisted mainly
of sedge, but even this was sparsely distributed. Pondweeds
(Potamogeton richardsonii, ~-zosteriformis, ~-friesii, and
~-vaginatus) formed beds covering approximately one third of
the lake bottom. Appendix 2 summarizes the physical and vege-
tative features.
NORMAN WELLS LAKES
The DOT floatplane base at Norman Wells is situated five
miles east-southeast of the townsite, on a lake one mile long
by 1/3 mile wide (area: 0.31 sq.mi.). The second lake sur-
veyed was immediately east-southeast of the above, and had
dimensions of one mile by ~mile (area: 0.24 sq.mi.). Forest
cover in the area consisted of open to scattered stands of
stunted black spruce.
-234 -
METHODS
EXPERIMENTAL LAKES
In order to obtain baseline data under undisturbed
conditions, camps were established on lakes adjacent to the
study area and observers walked to the study lake each morning.
Baseline counts of waterfowl (no disturbance) were made on the
first day. On the following four days a Cessna 185 landed
once an hour, taxied around the lake and took-off, for five
consecutive hours.
A baseline count of Lake 1 was made by two observers
in a canoe, in an attempt to find birds which were hiding in
emergent vegetation. On the following four days, waterfowl
were noted whenever they became visible to observers on shore
during the five-hour observation period. This method yielded
a fairly accurate picture of species and numbers on the lake
each day.
On Lake 2, hourly baseline counts were made from shore
on the first day, and on following days counts were made every
half hour. In all cases, normal waterfowl behavior and reaction
to the aircraft were noted from at least two points on shore.
LAKES AT NORMAN WELLS
The two lakes at Norman Wells are subject to continuous
disturbance during the open water season. Records obtained from the
Department of Transport (pers. comm. Norman Wells, N.W.T., Aug.
1972) indicate that aircraft used the lake for take-off or
-235 -
landing 1,182 times between 31 May and 11 August. These air-
craft ranged in size from Cessna 185's to De Havilland Twin
Otters (Figure 3). Aircraft taking off toward or approaching
from the southeast fly over the second lake at an altitude of
100 to 300 feet.
On 11 August, waterfowl on these two lakes were coun-
ted simultaneously for three hours by observers on shore.
Behavior of birds on both lakes was noted. The floatplane base was
subject to normal air traffic during this period.
RESULTS AND DISCUSSION
The waterfowl population on Lake 1 consisted primarily
of females with broods, while that on Lake 2 was composed almost
entirely of molting males. As normal behavior and reaction to
the aircraft were notably different for the two populations,
results are here presented separately.
LAKE 1
A summary of daily observations is presented in Table
1. Eight species were observed, four of these with broods.
Seventy-two percent of the individuals observed were brood
young. Only two birds were definitely identified as males -
two white-winged seaters which visited the lake briefly on 6
August.
The population of the lake remained stable at between
50 and 60 individuals during the course of the study (Figure 4).
-236 -
N
tN
-....)
TABLE 1. SPECIES AND NUMBERS OF WATERFOWL PRESENT ON LAKE 1 1 3-7 AUGUST 1 1972
August 3 August 4 August 5 August 6 August 7 Total
Species adult! young adult I young adult I young adult I young adul tT young adult1 young
Common Loon 2 2 2 4 4
Mallard 1 ~ 1 ~ 1 3
3
Green-winged Teal 2~ 4 5
1 ~ + 5
1
1 ~ + 5
American Widgeon 1 1 1 1 2 10
1 ~ + 10
Scaup 1 ~ + 7 1 ~ + 6 2 ~ + 23 2 ~ + 23 1 ~ + 6 3 31
1 ~ + 19 1 ~ + 17 1 ~ + 21
1 ~ + 3 1 ~ + 4 1 ~ + 7 1 ~ + 4
Goldeneye 1 !f 3~ 2~ 1 ~ 2 3
White-winged Scoter 1 2~ . 3
Surf Scoter 1 ~ + 6 1 ~ + 6 1 ~ + 6 1 ~ + 6 1 ~ + 6 3 6
2~ 2~
Unidentified Species 5 4 4 4 5
I
9 42 14 37 113 42 10 40 111 49 23 60
TOTALS 51 51 . 55 50 I 60 83
I
R 'd (see es1 ents text)
adult I young
2
1 ~ + 5
1
3~ + 31
2~
1 ~ + 6
4
10 46
56
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TOTAL NUMBER OF BIRDS OBSERVED
-238 -
These totals are somewhat misleading insofar as species com-
position changed slightly; however, at least 56 of the 82
individuals observed were considered to be resident on the lake.
Decisions as to whether or not individuals were resident were
necessarily somewhat subjective but were based on four consi-
derations: 1) how often the birds were observed; 2) position
on the lake; 3) normal behavior and reaction to the aircraft;
and 4) whether or not they were still present on the last
observation day. These decisions were simplified by the fact
that the majority of the birds were in broods, 82% of the resi-
dents being brood young.
There was very little movement in and out of the lake,
except for a few adult birds without broods and one brood which
disappeared before aircraft disturbance was begun. The increase
in the number of young on the last observation day was probably
due to improved visibility - a result of calmer weather condi-
tions than on previous days.
Table 2 summarizes normal behavior and reaction to the
aircraft for each species. Adult birds without young seemed
generally more sensitive to disturbance than brood females,
usually flying at the approach of the aircraft. Brood females
normally stayed with their broods. Young birds could not, of
course, resort to flight for escape, and broods either swam
away or dove, depending on the proximity of the aircraft. Broods
appeared not to be concerned by the disturbance unless the air-
craft was quite close. The only brood without a female (listed
as unidentified, but probably scaup) reacted in the same way as
-239 -
TABLE 2. NORMAL BEHAVIOR AND REACTION TO AIRCRAFT DISTURBANCE BY WATERFOWL ON LAKE
Reaction to Aircraft and
Species Normal Behavtor Frequency (No.) of Reactions NOTES
Common Loon swimming, flying fly, disappear 3 All observations on adults.
dive 1 Total of 6 flew from lake.
Mallard swimming, feeding fly, disappear 1 Two birds not on lake during count
flew by and disappeared.
Green-winged Teal swimming, feeding do nothing different 4 Female and brood.
swim away 3 Female and brood.
fly, disappear 1 Two females left lake.
American Widgeon swimming, feeding do nothing different 2 Adult.
N Scaup swimming, feeding, swim away 20 All observations on females and ~ resting, sleeping do nothing different 10 broods. Birds swam away slowly 0
dive 4 even when aircraft was up to 500
fly, land on lake again 2 yards away, more rapidly if air-
craft close. Dove only when air-
craft close or landed/took -off on
top of them.
Goldeneye swimming, feeding, fly, land on lake again 13 Observations on adult females.
resting swim away 1
fly, disappear 1
do nothing different 1
White-winged Scoter ----Two males landed but left
immediately.
Surf Scoter swimming, feeding, swim away 11 F ema I e and brood . Dove only
resting do nothing different 6 when aircraft landed close by.
dive 3
Unidentified species swimming, feeding do nothing different 3 Brood.
swim away 2
other broods.
Brood mixing was observed among the scaup. On several
occasions two of the broods, and occasionally all three, were
seen together. No permanent separation of a female from her
brood and no duckling mortalities were noted.
LAKE 2
Daily observations of species and numbers are summa-
rized in Table 3. Only two of the eight species observed had
broods. These were a brood of eight white-winged scoters, and
two immature red-necked grebes. Male scaup comprised approxi-
mately 90% of the original waterfowl population.
The waterfowl on this lake seemed generally intolerant
of aircraft activity, the total population being reduced to near
zero after four days. Figures 5 -10 show the successive decline
in the population with each disturbance.
Table 4 presents a summary of our observations of normal
behavior and reaction to disturbance for each species. Ninety-
eight birds flew off the lake in direct response to the aircraft,
74% of these on the first day. On subsequent disturbances, many
of the birds began swimming away even before the aircraft made
its final approach. Escape by diving was observed only when the
aircraft was very close. Waterfowl remaining on the lake resu-
med normal activities almost immediately after the plane had
left.
-241 -
TABLE 3. SPECIES AND NUMBERS OF WATERFOWL PRESENT ON LAKE 2, 10-14 AUGUST, 1972
T M E
Species 0730 0800 0830 0900 0930 1000 1030 1100 1130 1200 1230
Number
Common Loon 1
Red-necked Grebe 4 4 3 2 5 5
0 American Widgeon 2 2 2 6 5 4
Ring-necked Duck 5 3 -Scaup 136 144 158 158 128 127 "' ;:)
Bufflehead 2 2 2 2 2 2 C)
;:)
White-winged Scoter <( 9 9 9 6 1
Total 153 161 174 175 145 142
Arctic Loon 1 1 1 3
Red-necked Grebe 6 7 6 5 5 5 5 5 7 7 7
American Widgeon 1 1 1
Mallard -Ring-necked Duck 3 3
"' ;:) Scaup 126 120 83 83 64 61 50 50 46 46 44 C)
;:) Bufflehead 2 2 1 1 1 1 1 1 <(
Total 134 130 91 91 71 68 56 55 58 60 51
Arctic Loon 2 2 2 2 2 2 2 2 2 7 4
N Red-necked Grebe 4 5 4 6 5 6 5 5 6 7 6
Mallard 2 2 2 -Scaup 35 27 19 19 9 4 3 3 3 3 "' 2 ;:)
C) Bufflehead 1 1 1 ;:)
<(
Total 44 36 25 29 16 12 10 10 12 18 13
C") Arctic Loon 2 2 2 2 1 1
Red-necked Grebe 2 2 4 3 3 2 2 2 2 -Scaup 2 "' ;:)
C)
;:)
<( Total 2 2 6 7 5 2 2 4 3 3
Common Loon
Arctic Loon 1
"'¢
Red-necked Grebe 2 3 3 4 2 3 4 3 2 2 -Scaup 6 6 "' ;:)
Bufflehead C)
;:)
<(
Total 2 3 4 5 3 4 10 9 2 3
-242 -
FIGURE 5-NUMBER OF BIRDS OBSERVED ON LAKE 2 (NO DISTURBANCE)
200
190
180
-I
0
-I
l> r
150 z
c
N ~ 140
~ !D
VI IT1 130 ;;o
0 120
"T'I
~ 110
;;o
0 100 VI
0 90 z
r 80
l>
" IT1 70
60
50
40
30
20
10
0.
0730 0830 0930 1030 1130 1230
TIME
C\1
UJ
~
<l
.J
z
0
o-
WU.I
>U
o::z
UJ<l
(J')CD
mo::
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.....
(J')(/)
o-0
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CiiLL.
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O<l
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UJ .....
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<D
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Cl)
TOTAL NUMBER OF BIRDS ON LAKE
-244 -
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0
(/) 90
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" rn 60
50
40
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0
0730
FIGURE
0800 0830 0900
7-NUMBER
(SECOND
0930
OF BIRDS OBSERVED ON LAKE
DAY OF DISTURBANCE)
1000 1030 1100 1130
T !ME
2,
1200 1230
-t
0
-t
l>
r
z
N c
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tTl
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ID -
:0
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0 z
r
l>
;:>:;
tTl
200
150
100
90
80
70
60
50
40
30
20
10
FIGURE 8-NUMBER OF BIRDS OBSERVED ON LAKE 2
{THIRD DAY OF DISTURBANCE)
0~~~~~==~~~~~==~~~~
0730 0800 0830 0900 0930 1000 1030 1100 1130 1200 1230
TIME
-I
0
-I
l>
r
N +:> z -....] c
3:::
tD
I'T1
::0
0 ,
tD -
::0
0
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:;>:;
I'T1
200
150
100
90
80
70
60
50
40
30
20
FIGURE 9-NUMBER
(FOURTH
OF BIRDS OBSERVED ON
DAY OF Dl STURBANCE)
LAKE 2
'or :
0 t ! ~ ~ ' ~ :------. ! ~
0730 080C 0830 0900 0930 1000 1030 1100 1130 1200 1230
TIME
z
c
3:
Ill
ofTI ,::c
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00 Ill,
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200
100
FIGURE 10 -TOTAL BIRDS PRESENT ON LAKE 2 AT END OF DAILY
OBSERVATION PERIOD, 10-14 AUGUST, 1972.
r = 0.90
n = 5
P< 0.05 (I TAILED)
OL---~----~~~~~~ AUG. 10 II 12 14 13
DATE
TABLE 4. NORMAL BEHAVIOR AND REACTION TO AIRCRAFT DISTURBANCE OF WATERFOWL ON LAKE 2
Reaction to Aircraft and
Species Normal Behavior Frequency (No.) of Reactions NOTES
Common Loon feeding dive
Arctic Loon resting, feeding, fly and disappear 7 Total of 11 flew from lake.
swimming, flying dive 6
swim away 2
fly, circle lake, land
dive, then fly and
disappear
Red-necked Grebe resting, feeding dive 15
swimming swim away 5
fly and disappear 1 One flew from lake.
N do nothing different +:-
1.0
Mallard swimming fly, land on lake
fly, disappear 1 Two flew from lake.
Widgeon resting, feeding dive
dive, swim away
Ring-necked Duck no observations fly, disappear 1 Total of 3 males flew from lake.
Scaup resting, feeding, fly, disappear 8 Total of 80 flew from lake.
swimming dive 11
swim away 7
Bufflehead resting, feeding, fly, disappear 1 One male left lake.
swimming do nothing different
White-winged Seater resting, swimming --Female and brood left lake before
start of disturbance.
Some of the birds remaining on the lake appeared to
be flightless, but this could not be directly substantiated.
Kortright (1942} gives the peak of the flightless season as
between the end of July and the end of August. Our study,
conducted from 10 -14 August, was in the middle of this
period. All of the male diving ducks observed were in their
eclipse plumage, although the majority could fly. A number
of flightless ducks, particularly wigeon, were present on
other lakes during this period, so it is probable that a
number of the birds on the study lake were also flightless.
Throughout the course of the study there was some
movement of waterfowl not directly attributable to aircraft
activity. While we were gathering baseline data, 45 birds
left the lake and 17 flew in. On the following four days,
17 birds left the lake between disturbances, while 31 came
in. These observations were taken to be an indication of
general restlessness at this time of year. Our general im-
pressions was that a number of waterfowl were moving back and
forth among the many small lakes in the area.
The drastic decline in numbers on the study lake
cannot be totally accounted for by birds flying away, however.
Flightless birds may have left the lake overland, or utilized
either of two short streams connecting the lake with others in
the area. There is the possibility that the birds may have
remained hidden in emergent vegetation, although it seems
-250 -
unlikely that they would do so over the entire course of a
day's observations, especially since emergent cover was very
limited.
NORMAN WELLS
Species and numbers seen on the two lakes at Norman
Wells are given in Table 5. Our field notes indicate that
the arctic loons on the float base lake appeared to be undis-
turbed except when they were in the path of, or very close
to, a landing or departing aircraft. The scaup and red-necked
grebes, congregated at the northwest end of the lake, had air-
craft passing very low over them on landings but appeared to
pay little attention. Low-flying aircraft passing over the
second lake did not cause any noticeable change in behavior
of the birds.
IMPLICATIONS OF DISTURBANCE
Some preliminary remarks can be made on the implica-
tions of disturbance to waterfowl at this time of year. Some
waterfowl apparently become tolerant of aircraft activity, as
our results from DOT lake at Norman Wells show. This lake
supported a relatively low density of waterfowl (80 per sq.mi.
compared to peak densities of 250 per sq.mi. on Lake 1, 560
per sq.mi. on Lake 2, and 215 per sq.mi. on the second lake at
Norman Wells), but the lack of apparent reaction from the birds
-251 -
TABLE 5. SPECIES AND NUMBERS OF WATERFOWL PRESENT
ON LAKES AT NORMAN WELLS I 11 AUGUST I 1972
Species DOT Lake Second Lake
Arctic Loon 3
Red-necked Grebe 3 4 adults, 3 immatures
Scaup 10c3'd',9~~ 30C3'a',4~~'
9 immatures
Mallard 1 ~
TOTAL 25 51
-252 -
indicates that small numbers of birds, at least, are able to
withstand repeated disturbance.
There was a difference in the response of water-
fowl to aircraft disturbance on the two experimental lakes.
On Lake 1, which was essentially a brood-rearing lake, the
number of birds did not decrease as aircraft disturbance
increased (r = +0.359; n = 5; Table 1, Kendalls rank correla-
tion-Sokal and Rohlf 1969). However, on Lake 2, which was
used by molting and non-breeding birds, there was a marked
reduction in the number of birds using the lake as disturbance
continued (r = -0.900; n = 5; Figure 10, ibid). This indicates
that females with broods did not avoid the disturbance by
flight whereas non-breeding birds did.
Our studies were conducted on small lakes in order
to facilitate the observation of waterfowl behavior. The data
indicate that, for some species at least, reaction to distur-
bance depended on the proximity of the aircraft. Any delete-
rious effects might therefore be reduced on larger lakes.
It should be emphasized that our results are based
only on short-term and easily observed reactions. Longer-term
effects of disturbance, such as higher mortality of young or
desertion of molting areas by adults, are an additional possi-
bility. Sterling and Dzubin (1967) found that Canada Geese
deserted traditional molting grounds when subjected to harass-
ment.
-253 -
REFERENCES CITED
Anderson, R.M. 1913. Report on the natural history collections
of the expedition. Pages 436-527 In v. Stefansson,
My life with the Eskimos. Macmillan Co., New York.
538 pp.
Cooke, W.W. 1915. Bird migration in the Mackenzie Valley,
Auk 32:442-459.
Jones, E.T. 1956. Mackenzie River migration. Can. Field-
Nat. 70:143.
Kortright, F.H. 1942. The ducks, geese and swans of North
America. Wildl. Mgmt. Inst., Washington. 476 pp.
Davis, R.A. 1974. Aerial surveys of bird populations along
the route of the proposed gas pipeline in the
Mackenzi9 District, N.W.T. 1972. In Bird distri-
bution and populations ascertained~hrough aerial
survey techniques, 1972. C.A.G.S.L. Biol. Rep.
Series, Volume XI.
Sokal, R.R., and F.J. Rohlf. 1969. Biometry. W.H. Freeman
and Company, San Francisco. 776 pp.
Sterling, T., and A. Dzubin. 1967. Canada goose molt
migrations to the Northwest Territories. Trans.
N. Am. Wildl. and Nat. Resources Conf. 32:355-373.
-254 -
APPENDICES
APPENDIX 1 . PHYSICAL AND VEGETATIVE FEATURES OF LAKE 1
Coordinates: 121 °05' W 62°11' N
Average depth: less than 3'
Water color: brown
Bottom type: muck with some large rocks and gravel
Emergent vegetation: Sedge sp.
Submergent vegetation:
Shore I ine: low
Eleocharis sp.
Scirpus sp.
Equisetum sp.
Potamogeton richardsonii
P. gram ineus
Myriophyllum sp.
Hippurus sp.
S pargan i um sp.
Nuphar sp.
Utricularia vulgaris
-255 -
APPENDIX 2. PHYSICAL AND VEGETATIVE FEATURES OF LAKE 2
Coordinates:
Average depth: greater than 6 1
Water color: brown
Bottom type: muck
Emergent vegetation: Sedge sp.
Submergent vegetation:
Equisetum sp.
Eliocharis sp.
Potamogeton richardson ii
P. zosteriform is
P. friesii
P. vaginatus
Lemna trisulca
Spargan ium sp.
Myriophyllum sp.
Nuphar sp.
Polygonum sp.
Shoreline: sloping to abrupt; up to 10 ft. rei ief
-256 -
-LSG -
SHd'l8DOJ.OHd
FIGURES 1 and 2-Typical Southern Mackenzie Valley Lakes.
'·
FIGURE 3 -Twin Otter that used lakes at Norman Wells.
BIOLOGICAL REPORT SERIES
VOLUME FOURTEEN
DISTURBANCE TO BIRDS BY GAS COMPRESSOR
NOISE SIMULATORS, AIRCRAFT AND HUMAN
ACTIVITY IN THE MACKENZIE VALLEY AND
THE NORTH SLOPE, 1972
Edited by
W. W. H. GUNN, JOHN A. LIVINGSTON
Prepared by
L.G.L. LIMITED, ENVIRONMENTAL RESEARCH ASSOCIATES
FEBRUARY, 1974
CANADIAN ARCTIC GAS STUDY LIMITED
ALASKAN ARCTIC GAS STUDY COMPANY