Black Oystercatcher Haematopus bachmani

Transcription

1 Black Oystercatcher Haematopus bachmani Conservation Status Heritage Agency G Rank: G5 USFWS/NOAA: Bird of Conservation Concern S Rank: SS3B,SN SOA: Species of Greatest Conservation Need BLM: USFS: Sensitive Class: Aves Order: Charadriiformes AA: Yellow IUCN: Least Concern Final Rank Conservation category: VIII. Yellow VIII = low status and either high biological vulnerability or high action need Category Range Status: -0 to 0 - Biological: -50 to 50 - Action: -40 to Higher numerical scores denote greater concern Status - 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 Trend (-0 to 0) Thought to be stable, but survey data is limited, and trend data virtually nonexistent. Within Prince William Sound, numbers of pairs increased or remained constant between 99 and 998 (Murphy and Mabee 000). On Middleton Island, the total number of birds increased from two in 976 to 78 in 00 (Gill et al. 004). Number of breeding pairs has increased by 40% since 00, but has stabilized since 004 (Guzzetti and Talbot 008). Possibly extirpated from islands around Sitka, Alaska, where breeding numbers declined from 0 individuals in 940 to 4 individuals in 985 and 007 (Andres 008). A 003 survey of Glacier Bay National Park found 6 territorial adults (non-territorial birds were not censused) throughout the entire park, but in the area of greatest nest density (the only area in the park previously censused), the Beardslee Islands, the number of territorial adults had fallen from 8 in 995 to 56 (Arimitsu et al. 004). In the Rat Islands, surveys conducted between 003 and 007 demonstrate stable populations (Gill 008d). Distribution Trend (-0 to 0) The retreat of glaciers, which expose gravel moraines, and uplift from earthquakes can create new oystercatcher nesting habitat (Lentfer and Maier 995, Gill et al. 004). Habitat relatively pristine throughout their range. Increased tourism in Kenai Fjords may reduce use of these areas. The Alaska earthquake of 964 created an extensive rocky intertidal zone on Middleton Island. Since 976, the number of pairs has increased from one to 78 in 00 (Gill et al. 004). Status Total: Biological Population Size (-0 to 0) About 60% of global population (4,500-7,000) thought to reside in Alaska, mostly within the Kodiak Archipelago, throughout Prince William Sound, and Southeast Alaska (Andres and Falxa 995). Range Size (-0 to 0) - 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). In western Alaska, common throughout Aleutian Archipelago west to Kiska Island and locally in northern Bristol Bay (Eley 976, Niven and McClellen 987, Andres and Falxa 995). Most of the population occurs in southcentral Alaska where they are common throughout the Kodiak Archipelago and east to Kenai Fjords National Park and eastern Prince William Sound (Andres and Falxa 995). Recent colonization of Middleton Island in the Gulf of Alaska (Gill et al. 004). Regular along outer coast of southeastern Alaska. Occasionally found on the Pribilof Islands in winter (Rodstrom 984). ~83,69 km calculated - -

2 in ARCMAP. Population Concentration (-0 to 0) Does not concentrate during the breeding season (Andres and Falxa 995). Black Oystercatchers are known to concentrate in large groups in the winter (e.g on Kodiak in winter with groups around 600). The number of these large concentrations in Alaska is very likely less than 5, though the locations of these great concentrations remain largely unknown. It is also probable that a small proportion of the population winters in much smaller groups scattered along the coast at more than 5 total sites (Tessler, ADFG, personal communication). Reproductive Potential Age of First Reproduction (-5 to 5) In CA, first breeds at 5 yrs of age. Number of Young (-5 to 5) Clutch size ranges from -4 (usually -3). Ecological Specialization Dietary (-5 to 5) Feeds on mollusks (e.g., pries open mussels and limpets), probes sand for marine worms. Habitat (-5 to 5) Obligate inhabitants of intertidal zone. Habitat is exclusively associated with the high tide margin of the inter-tidal zone, and includes mixed sand and gravel beaches, cobble and gravel beaches, exposed rocky headlands, rocky islets, and tidewater glacial moraines. Breeding territories are usually in close proximity to dense mussel beds. In Alaska, highest breeding densities occur on non-forested islands dominated by sloping beaches of shell or gravel (Andres 998). In winter, flocks concentrate on protected, ice-free tidal flats with dense mussel beds (Hartwick and Blaylock 979). 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 (-0 to 0) In Prince William Sound, about,400 miles of shoreline, much of it rated high for oystercatcher habitat, has been protected by the Exxon Valdez Oil Spill Trustee Council, including Sheep Bay, Two Moon Bay, Bligh Island, and Chenega Island (Andres 998). Shoreline habitat around Kodiak Island is protected in Kodiak National Wildlife Refuge. Elsewhere, habitat is protected where species occurs in Kenai Fjords, Glacier Bay, and Katmai National Parks, and in Maritime and Alaska Peninsula/Becharof National Wildlife Refuges. Interagency conservation action plan for this species developed in April 007. Subsistence harvest permitted with regulations (USFWS 006c). Protected under the Migratory Bird Treaty Act (MBTA 98). Monitoring Needs (-0 to 0) Monitoring occurs in portions of their range (Prince William Sound, Western Aleutian Islands). within Alaska, but not state wide. Coordinated surveys needed range-wide to determine accurate population assessment. This includes implementing rigorously designed protocols for monitoring status and trends (Andres and Gill 000, Alaska Shorebird Working Group 004). Long-term monitoring of selected populations needed to assess population trends and viability. Winter surveys needed in Southeast Alaska to determine what proportion of the population utilizes this area. Research Needs (-0 to 0) Due to species dependence on inter-tidal habitats, it is vulnerable oils spills year-round (Exxon Valdez spill directly resulted in mortalities and was associated with a decline in breeding). Concern also due to increasing commercial and recreational vessel traffic and growing recreational use at breeding sites. Annual productivity in Kenai Fjords National Park was not associated with presence of camp sites. Egg and chick predation by mammals and birds is substantial (eradication of fox led to recolonization). Subsistence harvest affects local populations. Effects of shoreline disturbance and effects of increasing vessel traffic need study. Causes of declines in Sitka Sound remain unsolved, but possible explanations include development and an increase in Bald Eagles and Common Ravens (Andres 008). 0.8 There is also growing concern that pressure from recreational activities in and around breeding areas could have deleterious effects. Increasing pressure from the tourist industry in the form of growing visitation by cruise ships, sightseeing vessels, water taxis and private boats raises the likelihood that nests will be flooded by large wakes, especially during periods of high-

3 high tides. Increased human presence by campers, kayakers, and fishermen in remote coastal areas could interfere with parental care and foraging, may result in nest abandonment, and increases the likelihood that nests and eggs will be inadvertently trampled. Predation is the major cause of mortality to eggs and chicks; chicks are most vulnerable during the first weeks after hatching (Andres and Falxa 995). Clutches of chicks are regularly lost to high tides or storm surges (< 0% of all losses; Andres and Falxa 995). Eradication of foxes on several Aleutian islands resulted in recolonization by Black Oystercatchers (Byrd et al. 997). Decreased reproductive success in oystercatchers has been attributed to disturbance by pinnipeds, forcing adults to leave nest sites during incubation or brooding and by the actual crushing of eggs and chicks when hauling out (Warheit et al. 984). Subsistence harvest of either breeding adults or eggs is a potential threat to some local populations. Survey Needs (-0 to 0) Black Oystercatcher research is being conducted in Sitka Sound, the western Aleutians, on Middleton Island, Prince William Sound and during winter by tracking individuals during fall migration (Alaska Shorebird Group 008). Action Total: -0-5 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 Alaska Shorebird Group (ASG) Alaska shorebird conservation plan, nd edition. Unpubl. draft report. Available through U.S. Fish and Wildlife Service, Migratory Bird Management, Anchorage, AK. Alaska Migratory Bird Co-management Council (AMBCC) Subsistence harvest survey data Available online at: 3

4 Andres, B. A The effects of the Exxon Valdez oil spill on black oystercatchers breeding in Prince William Sound, Alaska. Exxon Valdez Oil spill State/Federal Natural Resource Damage Assessment Final Report (Bird Study Number /Restoration Study Nu Andres, B. A The Exxon Valdez oil spill disrupted the breeding of Black Oystercatchers. J. Wildl. Manage. 6: Andres, B. A Black Oystercatcher (Haematopus bachmani). Exxon Valdez Oil Spill Trustee Council Restoration Notebook. 8 pp. Andres, B Changes in breeding oystercatcher numbers in Sitka Sound, Alaska. Pp. 3 in Summaries of ongoing or new studies of Alaska shorebirds during 007 (J. Leibezeit, ed.), Alaska Shorebird Group. Andres, B. A., and G. A. Falxa Black oystercatcher (Haematopus bachmani). In: A. Poole and F. Gill (eds.). The Birds of North America No. 55. Academy of Natural Sciences, Philadelphia, PA, and American Ornithologists' Union, Washington, DC. 0 pp Andres, B. and R. Gill (eds.) A Conservation Plan for Alaska Shorebirds. Unpublished report. Alaska Shorebird Working Group. Available through U.S. Fish and Wildlife Service, Migratory Bird Management, Anchorage, Alaska. 47 pp. Arimitsu, M. L., M. D. Romano and J. F. Piatt Ground-nesting marine bird distribution and potential for human disturbance in Glacier Bay National Park and Preserve, Alaska. 003 Annual Report for National Park Service, Glacier Bay National Park and Byrd, G. V., J. C. Williams, Y. B. Artukhin, and P. S. Vyatkin Trends in populations of red-legged Kittiwake Rissa brevirostris, a Bering Sea endemic. Bird Conservation International 7: Eley, T. J., Jr Extension of the breeding range of the Black Oystercatcher in Alaska. Condor 78: 5. Gill, V. 008c. Black Oystercatchers surveys in the western Aleutian Islands. Pp. 3 in Summaries of ongoing or new studies of Alaska shorebirds during 007 (J. Leibezeit, ed.), Alaska Shorebird Group. Gill, V. A., S. A. Hatch and R. B. Lanctot Colonization, population growth and nesting success of Black Oystercatchers following a seismic uplift. Condor 06(4): Guzzetti, B. M. and S. L. Talbot. Breeding success, population trends, seasonal attendance, and genetic differentiation of Black Oystercatchers on Middleton Island, Alaska. Pp. 4 in Summaries of ongoing or new studies of Alaska shorebirds during 007 (J. Hartwick, E. B. and W. Blaylock Winter ecology of a Black Oystercatcher population. Stud. Avian Biol. :07-5. Lentfer, H. P. and A. J. Maier Breeding ecology of the Black Oystercatcher in the Beardslee Island region of Glacier Bay National Park. Pp in: D.R. Engstrom (ed). Proc. Third Glacier Bay Sci. Sym., 993, Natl. Park Service, Anchorage, AK. Migratory Bird Treaty Act (MBTA) of July 3, 98, Ch. 8, 40 Stat. 755 (98) (current version at 6 U.S.C ). Morrison, R. I. G., R. E. Gill, Jr., B. A. Harrington, S. Skagen, G. W. Page, C. L. Gratto-Trevor, S. M. Haig. 00. Estimates of shorebird populations in North America. Occasional Paper No. 04, Canadian Wildlife Service, Ottawa, Ontario, 64 pp. Morse, J. A., A. N. Powell, and M. D. Tetreau Productivity of Black Oystercatchers: effects of recreational disturbance in national park. Condor 08: Murphy, S. M. and T. J. Mabee Status of Black Oystercatchers in Prince William Sound after the Exxon Valdez oil spill. Waterbirds 3:04-3. NatureServe. 007b. NatureServe Explorer: An online encyclopedia of life [web application]. Version 6.. NatureServe, Arlington, Virginia. Available 4

5 Niven, D. K. and G. T. McClellen Summary of bird observations made in the Andreanof, Rat and Near Islands. United States Fish and Wildlife Service, Anchorage, AK. Rodstrom, W St. Paul seabird monitoring study 984, St. Paul, Alaska. Unpubl. rep. for City of St. Paul, Alaska. U.S. Dept. Interior, Fish and Wildlife Service, Anchorage, AK. 7 p. + appendices. Sharp, B Black Oystercatchers in Prince William Sound: oil spill effects on reproduction and behavior in 989. Unpublished USFWS Report. Bird Study Number. Sydeman, personal communication, in Andres, B. A., and G. A. Falxa Black oystercatcher (Haematopus bachmani). In: A. Poole and F. Gill (eds.). The Birds of North America No. 55. Academy of Natural Sciences, Philadelphia, PA, and American Ornithol Tessler, ADF&G, personal communication 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. Warheit, K. I., D. R. Lindberg, and R. J. Boekelheide Pinneped disturbance lowers reproductive success of Black Oystercatcher (Haematopus bachmani). Mar. Ecol. Prog. Ser. 7: 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