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Seabirds Lecture 10.

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Presentation on theme: "Seabirds Lecture 10."— Presentation transcript:

1 Seabirds Lecture 10

2 Common Groupings of Marine Birds
Seabirds—e.g. penguins, pelicans, gulls, terns Capable of feeding away from shore Breed on islands or coastal zones Shorebirds—e.g. sandpipers Feed on shorelines in sand/mud Wading birds—e.g. herons, egrets Freshwater or marine Marsh birds Hunters

3 Seabird Diversity 27 orders of birds—10,000 species
Four contain “true” seabirds Sphenisciformes—Penguins Procellariformes—Albatrosses, Petrels Pelecaniformes—Pelicans, Cormorants Charadriiformes—Gulls, Terns

4 Representative Families
Family Sternidae: Terns—45 species Slender, rapid wings Smaller than gulls Broad tail, often V-shaped Feed on fish at surface Many species highly migratory Royal Tern

5 Representative Families
Family Laridae: Gulls—56 species Intelligent Often adaptable to human disturbance Generalist carnivores The least specialized of all seabirds More generalized morphology Laughing Gull

6 Representative Families
Family Pelecanidae: Pelicans— species Feed on fish at surface Gular pouch on lower jaw One of the heaviest flying birds Brown pelican is smallest species Brown Pelican

7 Life History—Nesting Generally occurs at inaccessible coastal areas
Isolated islands, cliff faces, coastal wetlands Two reasons— Large nesting colonies Adults return to natal area Both parents involved with care

8 Life History—Offspring
Egg incubation  days Fledging period  1-2 months Juvenile seabirds often different plumage color 4-5 years until maturity Royal Tern Creche

9 Seabird Foraging—Gulls
Unhinging jaws— Take live prey Tool use Baiting, breaking shells Plunge diving Scavenging— Kleptoparasitism— Advantages of walking ability? Spring Summer Fall % of diet Starfish Mussels Crabs Herring Gull Dutch Colony

10 Seabird Foraging—Terns & Pelicans
Plunge diving—pelicans Only two species dive Impact on left side— Impact may stun fish Pelicans may also feed from surface Air sacs beneath skin and in certain bones— Plunge diving—terns Hovering Scavenging

11 Seabird Foraging—Terns

12 Seabird Foraging—other methods
Northern Gannet Dive from up to 100’ Depth of up to 50’ Swim with wings/feet

13 Seabird Foraging—other methods
Wilson’s Storm Petrel Most abundant bird Feeds on inverts and small fish

14 Seabird Plumage Coloration
Generally drab coloration White, black, gray, brown Often countershaded Adaptive significance poorly studied—hypotheses?

15 Bird Wings—overview Wings shaped like airfoils—
Secondary feathers  lift Primary feathers generate power—forward motion Greater flexibility of motion Connect to “hand” bones Large range of motion Wing cross-section Lift

16 Seabird Wings—high aspect ratio
Seabird wings not “slotted” to reduce drag Extended secondary region increases lift High apect ratio Good for soaring (gliding) Drawbacks? Albatross Grouse Tern Vulture

17 Seabird Wings—high aspect ratio
Dynamic Soaring

18 Seabird Wings—High-speed wings
Streamlined Greater proportion  primary feathers Good for sustained, high-speed flying Hovering Energetically expensive Albatross Grouse Tern Vulture

19 Seabird Osmoregulation
Nitrogenous waste  Uric acid Effective kidneys Salt Gland— Many seabirds still require some freshwater Pelagic seabirds  months to years at sea

20 Seabird Conservation Loss of nesting habitat Increased disturbance
Invasive species—nest predation Oil spills

21 Seabird Conservation Interactions with fishing gear
Long lines Gill nets Recreational entanglements Plastic pollution in ocean

22 Seabird Conservation—Success stories
Brown Pelican Listed as endangered—1970 Delisted 2009 DDT outlawed in 1972 Laughing Gulls Nearly extirpated in U.S. Late 1800s Plume hunters

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