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SCI-04 Natural History of Alaskan Seabirds • Session 3: Tuesday, 15 March 2016 • Today’s Topics – “Waterbirds” concluded (Loons) – Grebes – Gulls – (Terns, Jaegers: next session) – Order GAVIIFORMES Family Gaviidae: Loons • 5 species, both worldwide and in Alaska • large, heavy, foot-propelled divers • spear-shaped bills • legs positioned far back on the body • difficulty moving on land • Diving: reach depths of 75 meters and stay underwater to 8 minutes • young ride on their parents’ backs when small • long-lived, to 28 years • pair monogamously, typically for life Pacific Loon Gavia pacifica • Breeding adult: – Head and nape pale gray – White stripes on sides of neck – Throat patch iridescent purple • Vs Arctic Loon: Little or no white on flanks when sitting on water • Breeding distribution: NE Sibera to Hudson Bay • Winters along Pacific coast to Baja CA • Numbers – Alaska: 100,000-125,000 – Wintering areas: 1 million Arctic Loon, Gavia arctica • Breeding range: Scandinavia to western Alaska • No interbreeding with Arctic Loon where ranges overlap (NE Sibera, W Alaska) • In Pacific, winters along Asian coast • White on flanks of both immatures and adults Pacific and Arctic Loons • How, when did speciation occur? • Period of geographic separation (allopatry)? • Ice sheets at Last Glacial Maximum (~18,000 years ago) Red-throated Loon, Gavia stellata • Circumpolar distribution • Smallest loon • Breeding adult: – Pale gray head – Distinct red throat patch • Only rarely breeds far inland • Only loon to commute between nesting pond and ocean or larger lakes to feed • Winters along northern sea coasts • Numbers: – Alaska: 10,000 Common Loon, Gavia immer • (Tasingik = black-billed) • From Swedish: “lame” • Breeding adult: – black head – Necklace • Breeding range: Boreal biome of North America to Iceland • Winter: northern coastlines to Scandinavia • Note shape of bands on legs Common Loon • Numbers: – Alaska: 10,000 – Worldwide (NA): 250,000 • Demography – Age at 1st breeding: 6 years – Average breeding success: 0.5 fledglings – Annual survival: 92% – Average lifespan: 30 years – TYPICAL FOR LARGE SEABIRDS Yellow-billed Loon, Gavia adamsii • Inupiat: Tootlik • Bill: Straw-yellow bill • Breeding adult: – Black head, necklace • Breeding range: Central Canadian Arctic to northern Siberia • Winter range: Northern coastlines, Pacific and Atlantic • Rare – Alaska: 2,400 – Worldwide: ? – VIDEO:https://www.youtube.com/watch?v= kyRTu-VJM1Q Yellow-billed Loon territoriality • Pairs exclude both other Yellow-billed Loons and Pacific Loons from their territories • Graph: Numbers vs. Lake size on Colville River, Alaska – Note: Toolik Lake is 150 ha. – Interpretation: Pacific Loons co-occur on lakes with Yellow-billed Loons only if lakes are large with convoluted shorelines • Source: Haynes, T. B., et al. 2014. Journal of Avian Biology 45:296-304. Order PODICIPEDIFORMES • GREBES • 1 family (Podicipedidae), 6 genera, 19 species • Lobed, NOT webbed, toes • Floating nests • Parents carry their young on their back, even when diving Horned Grebe, Podiceps auritus • Small • Breeding adult (1 year-old plus): – Red eyes – golden horns back and above the eye • Distribution – Circumboreal – Breeds on small ponds and lakes (e.g., Smith Lake) – Winters along seacoasts (and inland water bodies in SE US) • Numbers – North America: 200,000 – Eurasia” ? Red-necked Grebe Podiceps grisegena • Circumboreal • Breeding adult: – Light gray cheeks – Reddish throat – Dark crown • Breeds on inland lakes • Winters along sea coasts • Numbers: – Alaska > 12,000 – Worldwide: ? Flightlessness in Grebes • 2 flightless species: – Titicaca Grebe (Lake Titicaca and nearby ephemeral lakes in wet years) – Junin Grebe: Lake Junin, West central Peru only – These 2 species are placed in different genera Charadriiformes: Phylogeny • 17 families, 360 species • Shared, unique features of skull, vertebral column, and syrinx • “Shorebirds and relatives” • Closest relatives: “Land birds” “Seabird” subgroups • Scolopaci – Phalaropes • Lari – Gulls and Terns – Skuas and Jaegers – Auks Phalaropes • Reversed sexual dimorphism – Females larger, showier, and compete with each other for mates • Sex role reversal: females never incubate Phalaropes • Non-territorial • Females compete directly for male mates • Once paired, a female produces a 4-egg clutch which that mate then incubates on his own • Female may then return to display area and attract a second mate, repeating the process • OR female may produce a 2nd clutch for 1st mate if 1st clutch is lost to predation • OR BOTH Phalaropes at Sea • Pelagic • Foods include copepods (small crustaceans) • Red Phalarope Red-necked Phalarope Phalaropes as seabirds • Chukchi Sea – >500,000 Red Phalaorpes (REPH) – 25% of all seabirds – vastly outnumber plantivorous auklets (6%) – Diet: Copepods – Lower graph • Left panel: oceanic copepod numbers • Right panel Calanus marshallae numbers Copepods • Small crustaceans – Planktonic or benthic – Free-living or parasitic – Unbelievable morphologies – Source: – Ernest Haeckel, Art forms in Nature. 1904 – https://en.wikipedia.org/wiki /Kunstformen_der_Natur Calanus copepods • Exceptional abundance in Bering and Chukchi Seas • C glacialis: 80% of zooplankton in arctic waters (ice edge blooms) Laridae (part): Gulls • Large diverse group with strong wings and powerful flight • Only several highly pelagic, most coastal, some inland • No large Larus gulls on the Pribilof Islands • 2-4 years to achieve adult plumage and maturity • Immatures often difficult to identify • Many nest colonially Black-legged Kittiwake Rissa tridactyla • Medium-sized, cliff-nesting gull, a true “sea gull” • yellow bill • Black legs, dark eyes • Gray mantle, wing tips dipped in black • Subarctic to Arctic, Circumpolar • About 2.5 million in Alaska, breeding wherever suitable sea cliffs occur Black-legged Kittiwakes: Numbers • Most-studied cliffnesting seabird species in Alaska • Numerous colonies: many years of counts • Trends: highly variable among colonies Black-legged Kittiwakes: When to count? • Numbers most consistent after all females have laid eggs and before any chick have fledged (one parent at nest, one at sea): counts should be during this period • Graph: Seasonal pattern of numbers (Semidi Islands, Hatch and Hatch 1988) Black-legged Kittiwakes: breeding success • Maximum clutch size: 3 eggs (VERY rare in Alaska, some years: zero) • Success ranges from 0 to 2 fledglings and varies markedly among years • Example: Bluff, a colony in Norton Sound • WHY? ________ Black-legged Kittiwakes: foods • Sand lance (red): Coastal colonies in Gulf of Alaska to Chukchi Sea • Gadids (cods, purple): Bering and Chukchi Seas • Myctophids (light blue): Pribilof Islands only • Annual variation: EXTREME • Poorly understood since no commercial fisheries on these fishes Brood reduction • Laying strategy: Lay number of eggs that will be successful in a good year • Incubation strategy: create inequities in case it’s not a good year • Late-hatched chicks: smaller, can’t compete for meals when food is limited • If die quickly, more food for other young • How to promote quick death in years of food shortage? Siblicide in seabirds • Facultative (kittiwakes): – NO: if food is abundant and larger older chick is fat and happy—rare in Alaska, though – YES: if larger older chick isn’t getting full meal deals • Vs. “Obligate (pelicans): – Older larger chick always kills smaller younger chick – Why lay 2 eggs? Insurance if 1st does not hatch – Lower photo: American White Pelican Red-legged Kittiwake, Rissa brevirostris • Red legs • Vs Black-legged: – Bill relatively short – Mantle darker gray – Black on wing tips not a distinct line – Eyes larger • ~200,000 (“Special Concern”) • VERY restricted breeding distribution – 80% on St. George Island Red-legged Kittiwakes: Prey • Broad overlap with Blacklegged Kittiwakes, BUT • Lanternfish (family Myctophidae) much more important in diet – Bioluminescent – Diel vertical migrations, near surface at night – Exceptionally high abundance in continental slope zone near St. George Island Red-legged Kittiwakes: nest site preference • “Character (competitive) displacement”: key component of niche that is not exploited by superior competitor. • Prefer narrow ledges at high elevations Ivory Gull Pagophila eburnea • • • • All white body Bi-colored, yellow-tipped bill Black eyes, black legs Most arctic of all birds; scavenger on arctic pack ice; global warming threat? Sabine’s Gull Xema sabini • • • • Small gull Black-white-gray wing pattern Slightly forked tail Breeding adult – Dark gray (black) hood – Bill black with yellow tip • Breeds in arctic coastal tundra regions • Winters in coastal upwelling zones in tropics, subtropics Any “sea gulls” in Fairbanks? • • • • Yes? ____ If yes, how many species? ____ No? ___ Note proper terminology: “gull”, NOT “sea gull” Bonaparte’s Gull, Larus philadelphia • Small gull • Breeding adult – Black hood – Black bill – Gray mantle with black wing tips – Orange-red legs • Nests in black spruces • Only “obligate” tree-nesting gull • In Alaska, breeds throughout boreal forest zone • Winters along NA coasts Ross’s Gull Rhodostethia rosea • • • • Small-bodied Variably light pink below Small black bill Breeding adult: thin black collar, orange legs • Breeds in Russian Far East; Winters in northern Alaskan waters • Focus of ecotourism at Barrow, late September-midOctober; WHY? ____ Ross’s Gulls in Fall • Chukchi Sea Lease Area • Entire Siberian population of Ross’s Gulls passes by Barrow, first to east and then to west • Only brief stay in Beaufort Sea • Recall offshore oil lease zones Ross’s Gulls: worst-ever specimens? • First specimens of this species at the US National Museum (Smithsonian) – Collected soon after Jeanette became mired in the ice (7 October 1879) – Carried until finally rescued more than 2 years later in northern Siberia by naturalist and taxidermist: Raymond Lee Newcomb Mew Gull, Larus canus (Nauygavak = beautiful gull) • • • • • Medium Size Small, all-yellow bill Yellow legs Wing tips splotched with black In Eurasia: Boreal zone, called “Common Gull” • In Alaska, breeds from crest of Brooks Range south • Common in Fairbanks in summer • Winters along Pacific coast • • • • • Herring Gull Larus argentatus Large body Pale gray mantle Pink legs and feet Bill yellow with red spot Circumboreal breeding distribution – Common in Fairbanks in Summer • Winters along coasts and inland Thayer’s Gull Larus glaucoides • Iceland Gull Subspecies thayeri • Breeding adult – – – – Eye dark brown Bill yellow with red spot Mantle light gray Legs dark pink • Alaska: Coastal migrant only between NE Pacific coast and High Canadian Arctic • Some winter in polynyas Slaty-backed Gull Larus schistisagus • Breeding adult: – Dark, slate-gray back and wings – Legs bright pink – Bill yellow with red spot – Eyes pale • Eurasian; breeding range extends to southern Seward Peninsula in Alaska Glaucous-winged Gull Larus glaucescens • Breeding adult: – Mantle pale gray – Above: primaries same color as rest of wing – Below: primaries lighter – Eyes DARK – Legs pink – Bill large, yellow, with red spot • In Alaska, breeding range extends north to central Bering Sea • Winters along Pacific coast to Baja CA Glaucous Gull, Larus hyperboreus • Large-bodied • All plumages: primaries white with translucent tips (all white distally) • Breeding adults: – – – – all white to light gray; Eyes YELLOW Legs pink Bill large, yellow, with red spot • Breeds along coast of western and northern Alaska and inland on North Slope • Winters along northern sea coasts and on Great Lakes