Double-crested Cormorants of the NY Harbor 2010 Harbor Herons and Waterbirds …

1. Double-crested Cormorants of the NY Harbor 2010 Harbor Herons and Waterbirds … Susan Elbin , New York City Audubon Liz Craig, New York City Audubon and Cornell University

2. Cormorants

3. Double-crested Cormorant Birds Banded in the NY Harbor

7. Gulls in Jamaica Bay 2010 Update Dr. Brian E. Washburn USDA, APHIS, Wildlife Services, National Wildlife Research Center 419-625-0242 brian.e.washburn@aphis.usda.gov

9. Research Objective Estimate the size of gull nesting populations in the Jamaica Bay Unit of Gateway NRA

10. Jamaica Bay Nest Count for 2010 20 islands & marshes May 27 to June 8, 2010 Multi-agency effort Count of adult gulls & count of gull nests

11. Count of Adult Gulls

12. Count of Gull Nests

13. JFKIA HERG

14. JFKIA GBBG

15. JFKIA LAGU

16. Research Objective Estimate the population of laughing gull nests in Jamaica Bay

17. Aerial Photography Approach

18. Number of LAGU Nests No estimate No estimate

21. Diet of Double-crested Cormorants in NY Harbor, 2010 update Colin Grubel, CUNY Graduate Center & Queens College John Waldman, Queens College

22. South Brother 4 collection trips 83 items identified 15 sp. fish, 1 crustacean Most common sp: Hogchokers (24%) & goldfish (22%) Swinburne 2 collection trips 72 items identified 18 sp. fish, 1 crustacean Most common sp: spotted hakes (29%) Colony comparisons

23. Conclusions • Swinburne results from trips close together • Can’t be easily extrapolated to rest of season • No new species found • Rarity of formerly popular species (scup, black seabass) and unusual popularity of hakes may be due to • South Brother surveyed more thoroughly than previous years • 1 new species (white sucker) • Bluegills, Lepomis macrochirus, and Pumpkinseeds, Lepomis gibbosus, usually common, not found

24. Investigations into the Factors Affecting Pellet Production

25. Introduction • Diet studies are an important part of management • Boli & pellets most common methods of diet assessment • Boli (regurgitated, partially digested food items) • Pellets (made up of bones, scales, otoliths and other indigestible items, contained in a mucous coat and regurgitated by the birds) • Otoliths are akin to ear bones of fish – highly species specific • Species not represented equally between pellets and boli • Good evidence of biases but no evidence as to exactly what is causing them

26. Feeding Trials • Prey spininess • Otolith morphology • Prey size • Two enclosures, housing 3 birds • Floors lined with Astroturf to prevent sand accumulation • Colored glass beads inserted into fish being fed out - help quantify the time each pellet has taken to form

27. Prey Spininess • Hypothesized that spines present on some species of fish may irritate the gut • Would speed up pellet production • Less time in gut would mean more otoliths surviving in pellet • Previous fieldwork indicated spininess as a possible factor affecting pellet production • 52%of fish identified in bolus samples were spiny, 48%were non–spiny • 95%of fish identified in pellets were spiny, 5%were non-spiny

28. Compact otoliths Croaker Scad Pinfish goldfish Fragile otoliths Threadfin herring False pilchard Otoliths by size Croaker (avg length 10.12µ) Scad (6.94µ) Pinfish (3.7µ) Large threadfin (3.57µ) Small threadfin & false pilchard (2.53µ) Goldfish* Otolith Morphologies

29. Conclusions • The timing of pellet production may be affected my spininess of prey species but results inconclusive • Length of captivity appears to play a part as well, reason unknown • Process may be different in wild birds • Otolith shape can affect the likelyhood of surviving to be ejected and identified in a pellet • Otolith size may also be important but more research needed