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HomeMy WebLinkAboutBradley Lake Trip Report Waterfowl Nesting Survey 1995TRIP REPORT WATERFOWL NESTING SURVEY BRADLEY LAKE HYDROELECTRIC PROJECT FOR LOCHER INTEREST LTD. DAMES & MOORE Mr. James H. Thrall Locher Interest Ltd. 8 DAMES & MOORE 5'·'~' B STREET, SUITE IUO. M\CHORAGE, ALASKA 99518-1641 (LJ07) 562-'.16h FAX: (907) 562-1297 August 8, 1995 406 West Fireweed Lane, Suite 101 Anchorage, AK 99503-2649 Dear Mr. Thrall: Trip Report: Waterfowl Nesting Survey Bradley Lake Hydroelectric Project D&M Job No. 21381-002-160 On July 13 and 14, I traveled to the Bradley Lake Project Site to conduct a waterfowl brood survey in the Waterfowl Nesting Area as a follow-up to the breeding pair survey conducted in late May of this year. This survey was conducted in the same area as the earlier survey on May 26 and 27, adjacent to the road and runway just west of the project facilities. After an initial reconnaissance of the area on the evening of July 13, I talked with employees at the site, Richard Turner and Greg Wells, on their observation of ducks in the area and whether they had seen any broods yet this summer. Richard Turner said he had observed at least two broods of ducks in the Waterfowl Nesting Area over the last several weeks but he was not sure of the exact species. Over the last several weeks, he had also seen a brood with a female duck in the slough on the north side of the runway outside the Waterfowl Nesting Area. The following morning (July 14) I carefully searched each of the islands for waterfowl nests or any sign of previous nesting activity (Figure 1). The islands and the back side of the impoundment were accessed by a small boat. The open-water areas and areas of emergent marsh vegetation within the Waterfowl Nesting Area were also scanned with a spotting scope for any duck broods or other waterfowl activity. Notes on vegetative cover and dominant species were recorded and photos were taken of representative vegetative species and habitats. Photos are enclosed in Attachment 1. I liT II'[:-, Wl l!ZLI l\X'[ I 1[ Locher Interest Ltd. August 8, 1995 Page 2 @ DAMES & MOORE A total of four broods were documented using the Waterfowl Nesting Area. Details are presented in Table 1. TABLE 1 WATERFOWL AND SHOREBIRD BROODS WCATED IN THE WATERFOWL NESTING AREA, BRADLEY LAKE PROJECT SITE Species Brood Size Comments Mallard 10 Young 75 percent the size of the adult. Located in thick sedge marsh habitat (Carex Lyngbieae). This may be a mixture of two broods. Mallard 2 Young mostly grown, located in sedge marsh habitat. American Wigeon 9 Located feeding along the perimeter of the center island in emergent sedge (Carex spp.) and mares tail (Hipperus tetraphylla). Young still downey. Green-winged Teal 8 Located along the perimeter of the islands with the Wigeon brood. Female Green-winged Teal returned and broods separated. Young still downey. Spotted Sandpiper l Chick approximately half grown but still downey. There could have been more hidden in the vegetation. The large size of the young in the two broods of Mallards tend to indicate the females were nesting somewhere other than on the artificial islands during late May, the time of the nesting survey, and moved the broods into the area after hatching. Young from both the Wigeon brood and the Green-winged Teal brood were quite small and may have nested on one of the islands after the nesting survey, since it was six weeks between surveys. Locher Interest Ltd. August 8, 1995 Page 3 g DAM~~ & MooRE The Green-winged Teal brood was probably from the nest found on the center island on June 22, after the initial survey on May 27 and 28. The nest was found by the field party fertilizing the islands (J. Thrall -personal communication). This nest was located on the back of the impoundment and was the first nest located on the islands (Figure 1). The remains of the nest site were checked on this survey and located under a cover of thick, dead grass at the edge of the island. Some small willow shrubs were within a half meter of the nest, which also provided some cover. An additional Green-winged Teal nest was located on July 14, when a female flushed from a nest with eight eggs located on one of the small islands at the western end of the area (Figure 1). This nest was also found under a cover of thick, dead grass similar to the first nest. The nest was just below a Common Raven nest located on a rock cliff face rising from the back side of the impoundment. The young Ravens had fledged by the time of this survey and the nest was no longer active. Both of these Green-winged Teal nests were approximately 1.5 meters from the water and just above the sideslope of the island. Finding an active nest this late in the season was unusual; however, there may still be enough time left for the young to develop by early fall. There was a strong correlation between the waterfowl observed using the Waterfowl Nesting Area in May and the broods located on this trip. The pair of Mallards, one lone male Mallard and two male Green-winged Teals seen in May corresponded to the three broods and one active nest found during this July survey. The one Wigeon brood may be associated with a lone male Wigeon that was seen flying over the impoundment in May. The exception was the Barrow's Goldeneye seen on the early survey, which were not observed in July. These birds probably moved to higher elevations to nest after the May survey. The sizes of the broods were generally within the normal range for these species and suggested that predation of young was not a serious problem up to this point in the season. There was no evidence that nest predation had occurred, although, since the overall nesting effort on the islands was apparently very low, there were very few nests to predate. Locher Interest Ltd. August 8, 1995 Page 4 --DAMES & MOORE The habitat within the Waterfowl Nesting Area appeared to be significantly more developed in comparison to late May and had developed into good brood-rearing habitat. Two species of sago pondweed (Potamageton pectinatus and P. vaginatus) were very well developed throughout the area. There was also a very healthy growth of filimentous green algae throughout the eastern portion of the impoundment. Emergent vegetation in the shallow water was also fairly well developed and consisted largely of arrow grass (Triglochin maritima), mare's tail, two species of sedge, and spike rush (Eleochirus sp.). Introduction of additional species of aquatic vegetation for waterfow 1 food does not appear to be necessary after the seeing the diversity of species on this trip. The vegetation on the islands in the eastern portion of the area appeared quite healthy and had the highest diversity of grasses, forbs, and woody species in the areas assessed. Small seedling spruce (Picea sitkana), Sitka alder (Alnus sinuata), cottonwood (Populus balsamifersa), willows (Salix spp.), and Kenai birch (Betula papyrifera) have sprouted on the tops of the islands. Other woody species include currants (Ribes spp.), highbush cranberry (Viburnum edule), and red elder (Sambuscus callicama). Some of the more prevalent forbs include lupin (Lupinus Nootkatensus), beach pea, (Lathyrum maritima), yarrow (Achillia borealis), fireweed (Epilobium angustifolium), and river beauty (Epilobium latifolia). Several species of grass occur on the islands but most appear to be introduced species from the original seeding for ground cover. Alkali grass (Puccinellia spp.) grows on the lowest areas of the islands, which are inundated by brackish water when the water level rises. The trees and shrubs showed good annual growth. Nesting habitat should continue to improve, especially if the fertilization program continues. The willows planted on the island are growing and doing fairly well, but it is expected that they will be browsed during the winter. There was some evidence of browse on the willows and alder by moose this summer. The vegetation on the islands in the western portion of the area had a lower species diversity and the soil appeared more impoverished than in the eastern portion. The lack of ground cover on these islands has, however, allowed a significantly greater amount of Sitka alder to invade. These islands will likely become covered with dense stands of alders, shading out much of the grass which is presently the dominant vegetation. The alder will provide some cover for nesting Locher Interest Ltd. August 8, 1995 Page 5 :g DAMES & MOORE waterfow 1 but generally crowds out other cover species. Lack of cover still appears to be the primary reason for the low nesting density of waterfowl on the artificial islands, although cover will increase as the shrub layer develops and the grasses and forbs become thicker. Surface water salinity was measured at several areas in the Waterfowl Nesting Area and was found to be generally between two and four parts per thousand (ppt). This was similar to the range found during the May survey. Surface water salinity measured on the seaward side of the runway was less than two ppt. This would tend to suggest that water which refills the impoundment during extreme high tides in summer is likely from the freshwater lens that develops from the runoff of local rivers and the tailrace of the powetplant. During the winter months, when river runoff declines, water which gets into the impoundment is probably of a much higher salinity. Other wildlife observed included a single set of wolf tracks found on the center island. The wolf appeared to be following a moose, which had wandered out onto one of the islands. Signs of river otter were also noted near the entrance of the stream on the south side of the impoundment. A Red-tailed Hawk was observed soaring over the area on several occasions but did not appear to be a threat to the young ducks. Conclusions: The Waterfowl Nesting Area appears to provide some nesting habitat for a small number of waterfowl, but only a few actually use the artificial islands for nesting at the present time. As the cover on the islands increases with the development of vegetation, use of the islands for nesting will likely increase. Brood-rearing habitat appears to be good throughout the impoundment. The rapid growth of the aquatic vegetation (an important food source) between the first survey in May and the second week in July was striking. There also appears to be an ample amount of cover provided by the emergent sedges and arrowgrass along the perimeter of the islands and the southern shoreline for the young and the flightless adults during molt. The habitat could easily support several more broods. Recommendations for maintaining or enhancing the Waterfowl Nesting Area for both waterfowl nesting and brood rearing habitat are presented below. Locher Interest Ltd. August 8, 1995 Page 6 8 DAMES & MOORE • Improve the water retention in the impoundment to stabilize water levels, and maintain the present low salinity of the water, • Continue to monitor the growth of the shrubs on the islands (especially the alder), its effect on cover for waterfowl, and whether some thinning might be required to enhance habitat. • Continue to fertilize the nesting islands to encourage the growth of the shrubs and to build up organic matter for cover. • Further encourage the development of cover species on areas where vegetation is sparse by adding organic material or adjusting the pH. If you have any questions regarding this survey or the recommendations in this report, please feel free to give me a call in Homer at 235-3487 or 235-7260. DEE:jc LOCHTRIP. RPT Sincerely, David E. Erikson Project Manager ~~~·~~ PLASIPAO •oAC nee TYPICAL SECTt.1N S!i "' . ,, f:f~~frf 1 ~~Q~~~~~·~1TF;~s~oRr ANO S.OR(Il>D ".fl TERJAL"""OVHil flJN!vtc.. M"L('I( ISL4.<./0S .fi"<J OVE.If COI-oST111JCT/Qfi C~. Sr~CJNC AR("IIo + )J.lt:' l.-'~ ·+ INTSI IC .. J. &·f) + ~ J50 ·· .. ·... . Gte~n~Wmge~· T~a · June .22, )995,. .. ~ TU"'"'EL MUCK ANO SHOT ,qOC)(1 ~tiTf:RIAL TQ B[ US€0 fO C'ONSTRu(T ~E:StiNC ISlA'-105 IEXCAVI\f[ tO.~L 4,8'1 10 , .. R£1"f0v£ tXIST!JoC COHCqtrE DROP 801( ""0 "L.UC CU.. \IERT EACH EJ.KJ AS S"«J'WH CW F7•3aJC: ITYP 6 L0CATION'$J 4S $1-iC»rnf 'WITH ~ ::,··~·:~;:+·~\:: ... :I· \:t·:: Figure l. Waterfowl Nesting Area Plan \!(;:~;':r,lt¥~r~ ,• +··· •:': P,qOPQSED CO'-TOU"S IT"rp, '~ fX15ri»C CON'OURI ""' , Tva 24' ¢ fl/Sr: .. c CL.lV!RtS 1$(( C'.IC ~~~ea-.r-r-~l-C rB-~,~ ~ ... ATTACHMENT 1 PHOTOS Photo 1 I Photo 2 Green-winged teal nest with eight eggs, July 14, 1995. Habitat where nest is located on the second island from the western end, July 14, 1995 . I Photo 3 Photo 4 Green-winged teal nest located on June 22, 1995 and photographed on July 13, 1995. Habitat where nest was found. Nest was located under a cover of dead grass, July 13, 1995. Photo 5 Stand of emergent arrow grass with filimentous green algae. I Photo 6 Thick growth of sago pondweed in shallow water. Photo 7 Photo 8 Best developed shrubs located on the eastern-most island, July 13, 1995. Dense grass and forbs on the eastern-most island, July 13, 1995. Photo 9 I Photo 10 Poorly developed vegetation in the center of the area, May 29 , 1995. Same area in July showing poor growth of grasses and forbs , July 13 , 1995 . ·Photo 11 Photo 12 Poorly vegetated portion of the center island, May 29, 1995. The same area in July showing poor growth of grasses and forbs on island but good growth of sedges along the perimeter, July 13, 1995. Photo 13 Photo 14 Sitka alder invading sparceJy vegetated area of western-most island , July 14, 1995 . Thick alder moving into grassy area.