Red-throated Loon Gavia stellata

Transcription

1 Red-throated Loon Gavia stellata Conservation Status Heritage Agency G Rank: G5 USFWS/NOAA: Bird of Conservation Concern S Rank: S4B,S4N SOA: Species of Greatest Conservation Need BLM: Watch USFS: Class: Aves Order: Gaviiformes AA: Red IUCN: Least Concern Final Rank Conservation category: IX. Blue IX = low status and low biological vulnerability and action need Category Range Status: -0 to 0-3 Biological: -50 to Action: -40 to 40-4 Higher numerical scores denote greater concern Status Population Trend (-10 to 10) 53% decline in 16 year span Growth rate of (CI=0.907, 0.976) in Arctic Coastal Plain for % above 005 estimate and 49% above 10 year average in AK- Yukon Waterfowl Breeding Population Surveys. Distribution Trend (-10 to 10) Localized surveys show both increases and declines in RTLO; spatial distribution appears to remain relatively stable over 50 years (Conant and Mallek 006, Larned et al. 006, Mallek et al. 006). 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 (-10 to 10) Estimated at 9,843 +,447 breeding individuals. This is thought to underestimate abundance in Alaska because some areas not surveyed and no visibility correction factors were incorporated. Alaska -Yukon waterfowl Breeding Population Survey 006 index estimated 13,300 breeders Range Size (-10 to 10) Winter across entire Pacific Coast of Alaska, but uncommon during winter in the Aleutian Islands and north coast of Alaska Peninsula. Most limited during winter, where range is approximately 60,000 km. Breed along coastal areas throughout Alaska, including Aleutians and Alaska Peninsula. Most common in northern and western Alaska. Population Concentration (-10 to 10) Does not concentrate. Nest in solitary pairs. May gather in small flocks adjacent to breeding areas. Flies in small flocks during migration. Reproductive Potential Age of First Reproduction (-5 to 5) Thought to be years. 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)

2 Number of Young (-5 to 5) Most clutches eggs, some 1 and rarely 3. May nest every year if conditions permit. Ecological Specialization Dietary (-5 to 5) 80% small fishes (39 species). Also, crustaceans, leeches, polychaetes, and mollusks. Habitat (-5 to 5) Typically select marshy islands for nest sites or on dry shores. Nest on small oligotrophic lakes in diverse habitats, such as forests, or tundra up to 1070 m.. Select partially drained shallow ponds with stands of Carex aquatilis. Select smaller ponds that thaw earlier. Availability of freshwater fish limits distribution; higher reproductive success was found for those nesting within 9 km of marine foraging habitat. During winter, occurs in shallow nearshore coastal waters, occasionally in fresh water lakes, reservoirs, slow-moving rivers. Found in shallow tidal areas in estuaries with submerged mud flats. During migration, move along rivers from lake to lake or lagoon to lagoon avoiding open seas. Biological Total: 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 (-10 to 10) Subsistence harvest is allowed (AMBCC 007). Protected under the Migratory Bird Treaty Act (MBTA 1918). Monitoring Needs (-10 to 10) Not monitored by BBS; Groves et al. (1996) has provided the most up to date trend and pop. estimate data. Christmas bird counts monitor this species, but winter counts not a reflection of breeding counts. Monitored in USFWS Eider Breeding Surveys and Waterfowl surveys. Research Needs (-10 to 10) Anecdotal evidence on reasons for large declines in Alaska, but no cause and effect relationships. Predation by red fox, arctic fox, wolf, jaegers, Herring Gull, Glaucous Gull, Sandhill Cranes, Bald Eagles is the major source of egg loss; chicks also preyed upon. Jaegers responsible for the majority of egg loss. Large declines were associated with changes in composition, distribution, and abundance of fish communities in the Gulf of Alaska and Prince William Sound. In Alaska, disturbance and habitat loss from oil and gas development on nesting grounds, fish availability, oil, mercury, and selenium contamination, climate change, subsistence harvest (considered relatively low) commercial fishing, entanglement in gill nets appear to be major human related threats. Survey Needs (-10 to 10) Breeding distribution is covered by the waterfowl breeding population survey (Conant and Mallek 006) and the eider breeding population survey (Larned et al. 005). Marine distribution year-round captured by shipboard and aerial censuses in the Gulf of Alaska and Bering Sea (Gould et al. 198). Action Total: 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. Not substantial Year-round % Global Range in Alaska: >10% % Global Population in Alaska: <5% Peripheral: Monotypic species No

3 References Alaska Migratory Bird Co-management Council (AMBCC) Subsistence harvest survey data Available online at: Armstrong, R. H Guide to the birds of Alaska, 4th ed. Alaska Northwest Books, Anchorage, AK. 3 pp. Barr, J. R., C. Earl, and J. W. McIntyre Red-throated loon (Gavia stellata). In: A. Poole and F. Gill (eds.). The birds of North America, No The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington, D. Bergman, R. D. and D. V. Derksen Observations on Arctic and Red-throated loons at Storkersen Point, Alaska, Arctic 30: Bundy, G Breeding biology of the red-throated diver. Bird Study 3: Conant, B. and E. J. Mallek Alaska-Yukon waterfowl breeding population survey: May 16 to June 6, 006. U.S. Fish and Wildlife Service, Juneau, AK. Cramp, S. and K. E. L. Simmons (eds.) Handbook of the birds of Europe, the Middle East, and North Africa: the birds of the western Palearctic. Vol. 1. Oxford Univ. Press, Oxford, U.K. Cramp, S. and K. E. L. Simmons. 1980b. Handbook of birds of Europe, the Middle East and North Africa. Vol. : Hawks to bustards. Oxford Univ. Press, New York. 695 pp. Davis, R. A A comparative study of the use of habitat by arctic loons and red-throated loons. Ph.D. diss., Univ. of Western Ontario, London. Derksen, D. V., T. C. Rothe, and W. D. Eldridge Use of wetland habitats by birds in the National Petroleum Reserve-Alaska. Resource Pub U.S. Fish and Wildlife Service, Washington, DC. 7 pp. Dickson, D.L The red-throated loon as an indictor of environmental quality. Can. Wildl. Serv. Occas. Pap. No. 73. Dickson, D.L Breeding biology of red-throated loons in the Canadian Beaufort Sea region. Arctic 46: 1-7. Douglas, S. D. and T. E. Reimchen Habitat characteristics and population estimate of breeding red-throated loons, Gavia stellata, on the Queen Charlotte Islands, British Columbia. Canad. Field-Naturalist 10:

4 Eberl, C Effect of food, predation, and climate on selection of breeding locations of Red-throated Loons (Gavia stellata) in the high arctic. Unpubl. M.S. thesis, University of Ottawa, Ottawa. Eberl, C. and J. Picman Effect of nest-site location on reproductive success of Red-throated loons (Gavia stellata). The Auk 110: Enquist, M How do Arctic skuas (Sterorcarius parasiticius) search for diver eggs? Ornis. Fenn. 60: Forbes, G., K. Robertson, C. Ogilvie, and L. Seddon Breeding densities, biogeography, and nest depredation of birds on Igloolik Island, N.W.T. Arctic 45: Furness, R. W Pages in Foula, Shetland, Volume 4. Birds of Foula. The Brathay Hall Trust, Amblesidae, Cumbria. Gabrielson, I. N. and F. C. Lincoln The birds of Alaska. The Stackpole Company, Harrisburg, PA and Wildl. Manage. Inst., Washington, D.C. 9 pp. Gould, P. J., D. J. Forsell, and G. J. Lensink 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. Groves, D. J., B. Conant, R. J. King, J. I. Hodges, and J. G. King Status and trends of loon populations summering in Alaska, The Condor 98: Harrison, C A field guide to the nests, eggs, and nestlings of North American birds. The Stephen Greene Press, Brattleboro, VT. Johnsgard, P. A Diving birds of North America. Univ. Nebraska Press, Lincoln, NE. 9 pp. Kessel, B Birds of the Seward Peninsula, Alaska: their biogeography, seasonality, and natural history. Univ. of Alaska Press, Fairbanks, AK. 330 pp. Larned, W. W., R. Stehn, and R. Platte Eider breeding population survey Arctic Coastal Plain, Alaska 005. U.S. Fish and Wildlife Service, Migratory Bird Management, Anchorage, AK. Larned, W. W., R. Stehn, and R. Platte 006. Eider Breeding Population Survey Arctic Coastal Plain, Alaska. USFWS, Migratory Bird Management, Waterfowl Branch. 56 pp. Larson, S On the influence of the Arctic fox (Alopex lagopus) on the distribution of arctic birds. Oikos 11: Mallek, E. J., R. Platte, and R. Stehn Aerial Breeding Pair Surveys of the Arctic Coastal Plain of Alaska. USFWS, Waterfowl Management. Pp: 5. Migratory Bird Treaty Act (MBTA) of July 3, 1918, Ch. 18, 40 Stat. 755 (1918) (current version at 16 U.S.C ). Merrie, T. D. H Relationship between spatial distribution of breeding divers and the availability of fishing waters. Bird Study 5: Pakarinen, R Red-throated diver. In the EBCC atlas of European breeding birds, W.M. Hagemeijer and M. Blair, eds.). Academic Press, New York. Palmer, R. S., ed Handbook of North American birds. Vol. 1: loons through flamingoes. Yale University Press, New Haven, CT. Reimchen, T. E. and S. Douglas Feeding schedule and daily food consumption in red-throated loons (Gavia stellata) over the prefledging period. Auk 101: Schamel, D. and D. M. Tracy Replacement clutches in the Red-throated Loon. J. Field Ornithol. 41: Soper, J. D Ornithological results of the Baffin Island expeditions of and , together were more recent records. Auk 63:1-4, 3-39,

5 U.S. Fish and Wildlife Service (USFWS). 003c. Migratory Bird Subsistence Harvest in Alaska; spring/summer subsistence harvest regulations for migratory birds in Alaska during the 003 subsistence season. Federal Register Vol. 68, No Wentworth, C Subsistence waterfowl harvest survey Yukon-Kuskokwim Delta. Comprehensive Report U.S. Fish and Wildlife Service. Anchorage, Alaska. 176 pp. Version date: 1//013 Report authors: K. Walton, T. Gotthardt, and T. Fields Alaska Natural Heritage Program University of Alaska Anchorage Anchorage, AK For details on the development of the ASRS and criteria, please see: Gotthardt, T. A., K. M. Walton, and T. L. Fields. 01. Setting Conservation Priorities for Alaska's Wildlife Action Plan. Alaska Natural Heritage Program, University of Alaska Anchorage, AK. 5