Sumich 1992MammalsBirdsReptilesAmphibiansSeabirdsSeabirds•8000 species of birds worldwide•~275 are “true” seabirds (only 3%!)•Oceans cover 70% of the globe•Why is it hard to be a seabird?Obtain virtually all their food from the seaTied to land for reproductionFood accessible primarily in coastal areasNo bird breeds at sea•Procellariformes = Tubenose birdswell-developed external nostrils92 speciesalbatross, petrel, shearwater•Pelecaniformes = Pelicans and relatives42 speciespelicans, herons, ibises, Five Orders of True SeabirdsNeed to know the scientific names of the five orders•Charadriformes = Gulls and relatives118 speciesGull, tern, auk, skua, puffin•Sphenisciformes = Penguins16 speciesFive Orders of True Seabirds•Suliformes = •Frigate Birds, Boobies, Gannets, Cormorants60 speciesFive Orders of True SeabirdsLevinton 2001Suliformes Fregataidae 5 Frigate BirdsPhalacrocoracidae 42 CormorantsPhaethontidae 13 Boobies, Gannets•Seabirds tend to be larger than land birds•Seabirds tend to lay larger eggs than land birds•Seabird eggs have long incubation times•Seabird chicks are reared by parents for a long timeCharacteristics of True SeabirdsClutch size smallExtended incubation and rearinPronounced parental care{•Only animal to breed in Antarctic winter•Males incubate eggs alone, holding between legs•Incubation time: ~115 daysExample of Pronounced Parental Care:Emperor PenguinMales can’t feed; eat snow for water;How do they go for so long without food?Ancel et al. 1997AloneAlone, enclosureSmall groupsNatural groups•Seabirds tend to be larger than land birds•Seabirds tend to lay larger eggs than land birds•Seabird eggs have long incubation times•Seabird chicks are reared by parents for a long time•Seabirds have adaptations for excess saltNasal glands concentrate salt up to 2-fold; release into nasal cavityExcrete uric acid rather than urea•Many seabirds nest coloniallyCharacteristics of True SeabirdsUric acid less toxic when concentrated,so decreased water lossin water, preySeabird Colonies•Nesting near sources of food•Benefits of colonial nesting•Seabirds tend to be larger than land birds•Seabirds tend to lay larger eggs than land birds•Seabird eggs have long incubation times•Seabird chicks are reared by parents for a long time•Seabirds have adaptations for excess saltNasal glands concentrate salt up to 2-fold; release into nasal cavityExcrete uric acid rather than urea•Many seabirds nest colonially•Many seabirds have well-developed olfactionOlfactory bulb large (37% of brain)Large surface area in noseCharacteristics of True SeabirdsJust 3% in forest songbirdsNevitt 1999“Tubenose” birdLarge surface area in noseSurfaces lined with special epithelial cells(Nevitt 2008)“Sniffing out Seafood”How do seabirds findzooplankton?Zooplankton feeding releases DMSDMS forms “olfactory feature”Testing the theory with blue petrel chicks…They may detect “olfactory features”…and with krill-scented oil slicks(Nevitt 1999)16Adaptations to life at sea: wing morphologyPelagic species: Longer wings, lower wing loadingDiving species: shorter wings17Dynamic SoaringSlope Soaring18Adaptations to life at sea: PlumageWaterproof plumage (except cormorants and some terns)Great Cormorant plumage: waterproof central part, wettable distal part. Grémillet et al., 2005Castro and Huber 2003•Aerial feedingSearch for food while flyingDrop to water to retrieve it (top few meters of water)Food includes fish, carrion, zooplankton, dungAlbatross, shearwater, pelican, gull, tern, etc.Feeding Methods of SeabirdsCastro and Huber 2003•Diving and SwimmingSwim in pursuit of preyUse webbed feet (cormorant) or wings (penguin)Can capture food at much greater depthsCormorants, tropic birds, puffins, auks, penguinsFeeding Methods of SeabirdsMilne 1995•Forage at sea for 4-8 days•Return to feed chicks•Radiotracking of feeding adultsKing Penguins DivingMake up to 300 dives/dayDive to 200 mUnsuccessful on 90% of diveEmperor Penguins•Excellent swimmers, divers•Regurgitates food to chicksCastro and Huber 2003•KleptoparasitismFeed on food or eggs of other birdsGrabbing food, pulling feathers, forced regurgitationOpportunistic: rob visible food, attack intraspecificallySpecialized: specialized adaptations, not intraspecificFrigate bird, skua, gull, ternFeeding Methods of SeabirdsSmall bodyLarge wingsUnwebbed feetCryptic coloration•KleptoparasitismSuccess rate ~25%Significant source of foodSummary of Seabird Diets:71% of species eat fish66% of species eat zooplankton28% of species eat squid•Feeding tripsDuring reproductive periodMovements between feeding and nesting areasBreeding colonies can be 1000 km from food•MigrationDirected movement along predictable routesSeasonal patternArctic Tern: 13,000 km between Arctic and Antarctic•WanderingNomadic wandering throughout rangeUnpredictable, not along predetermined routesAlbatross, auk, petrel, gullMovements of SeabirdsLongest known bird migration•Male and female take turns incubating single egg•Other partner forages for fish, fish eggs, squid•Stores food in “proventriculus”; separates water-soluble from fat-soluble components•Immatures reach sexual maturity in 10 years•Live up to 80 years •After chick fledges, adults wander for 2 years before breeding againWandering AlbatrossFed to chick•47 birds tracked initially; 22 loggers retrieved•15 round-the-world journeys•Shortest time: 46 daysGray-Headed AlbatrossFig. 1. (A to D) Representative migration routes of four gray-headed albatrosses in the 18 months between breeding attempts.J. P. Croxall et al., Science 307, 249 -250 (2005) Birds tagged while rearing chicks on Bird IslandMany circumnavigations at 950 km per day; mostly males(Veit et al. 1996)Long-term changes in seabird populations?Quarterly studies in the California Current for 10 yearsTemperature increased by 2oCTotal bird abundance declined by 40%3031Average Winter (June-August) TemperaturesPalmer LTER32Ducklow et al., 200733Palmer