Black Scoter Melanitta americana

Transcription

1 Black Scoter Melanitta americana Conservation Status Heritage Agency G Rank: G5 USFWS/NOAA: S Rank: S3S4B,S3N SOA: Species of Greatest Conservation Need BLM: Sensitive USFS: Class: Aves Order: Anseriformes AA: Red IUCN: Least Concern Final Rank Conservation category: I. Red I = high status, biological vulnerability, and action need Category Range Status: -0 to 0 6 Biological: -50 to Action: -40 to 40 Higher numerical scores denote greater concern Status Population Trend (-0 to 0) Breeding populations declined about 3.% (compared to 7 and 5 years ago) annually from in western Alaska (Stehn et al. 006). Currently below historic levels (ADFG 005). In a review of the 0 year period from 977 to 997, Conant and Groves (997) noted that the decline of scoters was most prominent in Waterfowl Production Units (WPUs) comprised of tundra habitat (Bristol Bay, Yukon Delta, Seward Peninsula, and Kotzebue Sound WPUs). The 006 survey indicated an increase above the 0 year average (Conant and Mallek 006). A comparison of March mean counts at Shemya Island over four years (993-96) indicated no trend (9.4, 78.0, 43.0, 47.5 birds/month) (Durand and Benjamin 993, Lipinski and Thomson 994, Meehan et al. 996, and Meehan and Krom 997). A study of seasonal abundance of waterbirds at Adak Island reported no difference between a six year period in the late 980's and a five year period in the early 990's (3.8 birds/survey and 30. birds/survey, Rojek et al. 995). However, winter surveys from the 970s (Byrd et al. 974) compared to the 990s, suggested a decline in wintering black scoter at Adak Island. Byrd et al. (974) reported flocks up to 300 birds on Clam Lagoon and Kuluk Bay during the years , compared to 0 to 60 birds from (Rojek et al. 995). In conclusion, quantitative data that could indicate a statistically significant trend specific to Black Scoters is lacking. The significant negative trend (p=0.05, ) reported by Hodges et al. (996) provides strong evidence of an annually variable but continuing long-term decline in overall breeding scoters in Alaska (Conant and Groves 997). Distribution Trend (-0 to 0) Unknown. Biological - variables measure the trend in a taxon s population status or distribution. Higher status scores denote taxa with known declining trends. Status scores range from -0 (increasing) to 0 (decreasing). Population Size (-0 to 0) For Alaska, a very gross estimate of 5,000 breeding pairs has been proposed (Bordage and Savard 995). Visibility corrected estimates of breeding population in western Alaska for was 08,00 (SE-3,300). Range Size (-0 to 0) Status Total: - variables measure aspects of a taxon s distribution, abundance and life history. Higher biological scores suggest greater vulnerability to extirpation. Biological scores range from -50 (least vulnerable) to 50 (most vulnerable). The Black Scoter breeds in of Waterfowl Production Units (WPUs) monitored by the U.S. Fish and Wildlife Service, Migratory Bird Management, Anchorage (Hodges et al. 996) (Figure ):Arctic Coastal Plain, Kotzebue Sound, Seward

2 Peninsula Koyukuk, Innoko, Yukon Flats, Tanana-Kuskokwim, Nelchina, Yukon Delta, Kenai-Susitna, Bristol Bay, Occasional low numbers on the Copper River Delta. Black Scoters winter widely across Alaska's southern coast from the Aleutian Islands to Southeast Alaska, and south along the Pacific coast to Baja California (Bordage and Savard 995). Black Scoters molt in large flocks from Cape Romanzof, Angyoyaravak Bay, Kuskokwim Bay, and south in bays to Cape Pierce (Palmer 976, King and Dau 98). There are also large concentration molting areas in the Gulf of Alaska, off Cape Yakataga (Goudie et al. 994), and possibly off Cape Suckling (Henny et al. 995). Molting range most limited, but uncertain of size. Wintering range 37,000 km. Population Concentration (-0 to 0) Black Scoters molt in large flocks from Cape Romanzof, Angyoyaravak Bay, Kuskokwim Bay, and south in bays to Cape Pierce (Palmer 976, King and Dau 98). There are also large concentration molting areas in the Gulf of Alaska, off Cape Yakataga (Goudie et al. 994), and possibly off Cape Suckling (Henny et al. 995). ~9 to 4 molting concentration areas? Reproductive Potential Age of First Reproduction (-5 to 5) Minimum age thought to be years (Palmer 976). Number of Young (-5 to 5) Usually 8 or 9, but ranges from 5 to 0 (Bordage and Savard 995) Ecological Specialization Dietary (-5 to 5) Except in inland habitats, mollusks comprise a majority of the diet; the blue mussel (Mytilus edulis) often is a major food (Bellrose 976). Also eats crustaceans, some fishes and plant foods, the latter being most important in inland habitats. Habitat (-5 to 5) Nests near lakes and pools on grassy or brushy tundra and in northern taiga (AOU 983). Usually nests close to water. In Quebec, Black Scoters used shallow (<5 m) lakes, generally with till or rock substrate (Bordage and Savard 995). They preferred lakes <0 ha in area, but also used lakes up to 00 ha. On the Yukon-Kuskokwim Delta, Black Scoters used disturbed areas such as river banks and sloughs, preferring areas of tall grass used to conceal nests (C.P. Dau personal communication in Bordage and Savard 995). The nest is a depression lined with plant material, down and feathers. Winter habitat requirements are poorly understood. Black Scoters prefer areas with gravel and cobble substrates, similar to areas favored by Harlequin Ducks (Histrionicus histrionicus) (Bordage and Savard 995). Palmer (976) states that among scoters, the Black Scoter is most likely to occur in exposed areas and on open water rather than seek shelter in a bay or calmer water. All males and some females generally molt at sea. Biological Total: -6 Action - variables measure current state of knowledge or extent of conservation efforts directed toward a given taxon. Higher action scores denote greater information needs due of lack of knowledge or conservation action. Action scores range from -40 (lower needs) to 40 (greater needs). Management Needs (-0 to 0) This species is harvested for subsistence (USFWS 006c) and hunting (ADFG 006a). There are a number of large protected areas in Alaska where Black Scoters are known to breed (Bordage and Savard 995). These include: Yukon Delta National Wildlife Refuge, Bering Land Bridge National Preserve, Selawik National Wildlife Refuge, Cape Krusenstern National Monument, Alaska Maritime National Wildlife Refuge, Yukon Flats National Wildlife Refuge, Possibly small numbers in the Minto State Game Refuge, Koyukuk National Wildlife Refuge, Kanuti National Wildlife Refuge, Nowitna National Wildlife Refuge, Becharof National Wildlife Refuge, Kodiak National Wildlife Refuge. Protected under the Migratory Bird Treaty Act (MBTA 98). Development of the North American Waterbird Management Plan and Sea Duck Joint Venture highlight protection of sea ducks in general, no specific actions benefitting Black Scoters have been undertaken. Monitoring Needs (-0 to 0) Quantitative data that could indicate a statistically significant trend specific to Black Scoters is lacking. Waterfowl surveys do not distinguish between species of scoter. Black Scoters were captured, using floating mist-nets in April 003 at Nelson Lagoon, located on the Bering Sea side of the Alaska Peninsula in order to understand timing of movement in relation to surveys (USGS 003).

3 Research Needs (-0 to 0) Contaminant influence on the health of molting or wintering Black Scoters during energetically stressful periods may be a contributing factor to overall population declines of scoter species in Alaska (Henny et al. 995). Additionally, the influence of atmospherically transported pollutants on arctic and sub-arctic breeding areas remains an uninvestigated factor potentially affecting population-level reproductive performance and individual long-term health and survival (Henny et al. 995). Given the overall high level of subsistence hunting of many species (Wentworth and Seim 996), particularly in tundra habitats in western Alaska during the last three decades (Raveling 984), the potential exposure to deposited lead shot in wetland ponds may be a factor influencing adult female survival and fecundity of diving ducks, including the Black Scoter (Flint et al. 997). Highly variable reproductive success from year to year makes high levels of adult survivorship crucial to ensure persistence of the species. Therefore, Black Scoters are particularly sensitive to hunting pressure, which selects for relatively high levels of adult mortality (Goudie et al 994, Bordage and Savard 995). Survey Needs (-0 to 0) Knowledge of Black Scoter distribution has been limited by the timing and incomplete coverage of breeding areas by the Waterfowl Breeding Pair Survey (Conant and Groves 00). As a result, Black Scoters were captured, using floating mistnets in April 003 at Nelson Lagoon, located on the Bering Sea side of the Alaska Peninsula in order to identify breeding, molting and wintering habitats (USGS 003). Marine distribution year-round captured by shipboard and aerial censuses in the Gulf of Alaska and Bering Sea (Gould et al. 98). Action Total: -4 Supplemental Information Harvest: Seasonal Occurrence: Taxonomic Significance: Range Map - variables do not receive numerical scores. Instead, they that are used to sort taxa to answer specific biological or managerial questions. Substantial, regulations Year-round % Global Range in Alaska: <0% % Global Population in Alaska: <5% Peripheral: Monotypic species No References 3

4 Alaska Department of Fish and Game (ADFG). 005a. Our wealth maintained: a strategy for conserving Alaska s diverse wildlife and fish resources, a Comprehensive Wildlife Conservation Strategy emphasizing Alaska s nongame species. Submitted to the U.S. Fis Alaska Department of Fish and Game (ADFG). 006a Migratory Bird Hunting Regulations Summary. Anchorage, AK. Alaska Migratory Bird Co-management Council (AMBCC) Subsistence harvest survey data Available online at: American Ornithologists' Union (AOU) Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp. Bellrose, F. C Ducks, geese and swans of North America. Stackpole Books, Harrisburg, PA. Bordage, D. and J. L. Savard Black Scoter (Melanitta nigra). No. 77 In A. Poole and F. Gill (eds.). The Birds of North America. The Academy of Natural Sciences, Philadelphia, and The American Ornithologist's Union, Washington, D.C. Byrd, G. V., D. D. Gibson, and D. L. Johnson The birds of Adak Island, Alaska. The Condor 76: pp. Conant, B. and D. J. Groves Alaska-Yukon waterfowl breeding population survey, May 5 to June 4, 997. U.S. Fish and Wildl. Serv. Rep., Juneau, AK. 9 pp. Conant, B. and E. J. Mallek Alaska-Yukon waterfowl breeding population survey: May 6 to June 6, 006. U.S. Fish and Wildlife Service, Juneau, AK. Dau, C.P., personal communication in Bordage, D. and J.L. Savard Black Scoter (Melanitta nigra). No. 77 In A. Poole and F. Gill (eds.). The Birds of North America. The Academy of Natural Sciences, Philadelphia, and The American Ornithologist's U Durand, A. and N. Benjamin Trip report: winter wildlife and oil contamination survey, Shemya I., Alaska. -6 March 993. U.S. Fish and Wildl. Serv. Rep. AMNWR 93/4. Adak, AK. 9 pp. Flint, P. L., M. R. Petersen, and J. B. Grand Exposure of Spectacled Eiders and other diving ducks to lead in western Alaska. Canadian Journal of Zoology 75: Goudie, R. I., S. Brault, B. Conant, A. V. Kondratyev, M. R. Petersen, and K. Vermeer The status of sea ducks in the north Pacific rim: toward their conservation and management. Trans. N. Am. Wildl. Nat. Res. Conf. 59:7-49. Gould, P. J., D. J. Forsell, and G. J. Lensink. 98. Pelagic distribution and abundance of seabirds in the Gulf of Alaska and eastern Bering Sea. U. S. Fish and Wildlife Service, Biol. Serv. Prog., Anchorage, AK. Henny, C. J., D. D. Rudis, T. J. Roffe and E. Robinson-Wilson Contaminants and sea ducks in Alaska and the circumpolar region. Environ. Health Perspect. 03(Suppl. 4):4-49. Hodges, J. I., J. G. King, B. Conant, and H. A. Hanson Aerial surveys of waterbirds in Alaska : population trends and observer variability. National Biological Service Information and Technology Report 4. 4 pp. King, J. G. and C. P. Dau. 98. Waterfowl and their habitats in the eastern Bering Sea. Pp In D.W. Hood and J.A. Calder (eds.). The eastern Bering Sea shelf: its oceanography and resources. Vol.. National Oceanic and Atmospheric Administration Lipinski, L. and G. Thomson Trip report: winter wildlife survey, Shemya I., Alaska. -8 March 994. U.S. Fish and Wildl. Serv. Rep. AMNWR 94/03. Adak, AK. 5 pp. Madge, S. and H. Burn Waterfowl: an identification guide to the ducks, geese and swans of the world. Houghton Mifflin Co., Boston. 98 pp. Migratory Bird Treaty Act (MBTA) of July 3, 98, Ch. 8, 40 Stat. 755 (98) (current version at 6 U.S.C ). 4

5 Meehan, J. P., and M. A. Krom Winter wildlife surveys at Eareckson Air Station, Sheyma Island, Alaska - winter 995/996. Final report for U.S. Air Force work order number 855. Prepared for U.S. Air Force, 6th Air Support Group, Civil Engineer Meehan, J. P., M. A. Krom, J. C. Williams, and L. M. Scharf Winter wildlife surveys at Eareckson Air Station, Shemya Island, Alaska, winter 994/995. Final report for Department of Defense Legacy project number 79. Prepared for U.S. Air Force, 6 Palmer, R. S. (ed.) Handbook of North American birds. Vol. 3. Waterfowl. Eiders, wood ducks, diving ducks, mergansers, stifftails. Yale Univ. Press, New Haven, CT. 560 pp. Raveling, D. G Geese and hunters of Alaska's Yukon Delta: management problems and political dilemmas. Trans. N. Am. Wildl. Nat. Res. Conf. 49: Rojek, N. A., J. P. Meehan and J. C. Williams Seasonal abundance of waterbirds at Adak Naval Reservation, Alaska, 99 to 995. Department of Defense Legacy project numbers 400 and 658. U.S. Fish and Wildl. Serv. Rep. AMNWR 95/09. 6 pp. Stehn, R., R. Platte, P. Anderson, F. Broerman, T. Moran, K. Sowl, and K. Richardson Monitoring Black Scoter population in Alaska, 005. U. S. Fish and Wildlife Service, Anchorage. U.S. Fish and Wildlife Service (USFWS). 006c. Regulations for the 006 Alaska subsistence spring/summer Migratory Bird Harvest. Alaska Migratory Bird Co-Mgt Council, U. S. Fish and Wildlife Service, Anchorage, AK. U.S. Geological Survey (USGS) Characterization of annual migration and habitat use of Black Scoters staging on the Alaska Peninsula. USGS, Anchorage, AK. Accessed online at Wentworth, C. and S. G. Seim Subsistence waterfowl harvest survey Yukon-Kuskokwim Delta. U.S. Fish and Wildl. Serv., Migratory Bird Manage., Anchorage, AK. 36 pp. Version date: //0 Report authors: K. Walton, T. Gotthardt, and T. Fields Alaska Natural Heritage Program University of Alaska Anchorage Anchorage, AK 9950 For details on the development of the ASRS and criteria, please see: Gotthardt, T. A., K. M. Walton, and T. L. Fields. 0. Setting Conservation Priorities for Alaska's Wildlife Action Plan. Alaska Natural Heritage Program, University of Alaska Anchorage, AK. 5