1. Colonial Waterbirds Nesting on the Niagara River, 1976-2011. Dave Moore 1 Francie Cuthbert 2 Chip Weseloh 1 Linda Wires 2 Niagara River RAP Implementation Committee Session 10 Apr. 2013 Niagara College, Niagara-on-the-Lake, ON 1 Canadian Wildlife Service 2 University of Minnesota

2. Page 2 Objective of surveys: To visit all islands on the Great Lakes and to census all species of colonial waterbirds that nest there (n=16). They are conducted at approx. 10 year intervals: Census 1 = 1976-80 Census 2 = 1989-91 Census 3 = 1997-2000 Census 4 = 2007-09 The Great Lakes Bi-national Decadal Colonial Waterbird Survey

3. Page 3 Great Black-backed Gull Herring Gull Ring-billed Gull Common Tern Caspian Tern Double-crested Cormorant Great Blue Heron Great Egret Black-crowned Night-Heron The Great Lakes Bi-national Decadal Colonial Waterbird Survey Forster’s Tern Black Tern American White Pelican SNEG CAEG LBHE BOGU LIGU

4. Page 4 Methods Census nests late in incubation or brooding Count all AONs Approximate Census Timing: 8-30 May = Gulls (& scouting for other species) 1-7 June = Common & Caspian Terns 10-30 June = Cormorants and Herons Census Methods: Preferred Method = Ground count (of individual nests) Other Methods = - extrapolation from ground counts - boat estimates - aerial surveys - estimates from aerial photographs

5. Page 5 Niagara River – colony distribution Lake Ontario Niagara River Lake Erie USA Canada

6. Page 6 Niagara River – abundance & trends Double-crested Cormorant 2 3 3 4 Nests 3 5

7. Page 7 Niagara River – abundance & trends Black-crowned Night Heron 1 3 3 2 1 1 Nests

8. Page 8 Niagara River – abundance & trends Great Blue Heron 0 0 1 1 Nests

9. Page 9 Niagara River – abundance & trends Great Egret 00 5 1 Nests * * 17 nests at 2 sites in Canada in 2012 1

10. Page 10 Niagara River – abundance & trends Common Tern 2 3 5 4 Nests 1 3

11. Page 11 Niagara River – abundance & trends Herring Gull 3 2 5 13 Nests 1 5 2 3 3 3

12. Page 12 Niagara River – abundance & trends Ring-billed Gull 1 1 5 2 Nests 1 2 2 4 6

13. Page 13 Niagara River – abundance & trends % total nests Species composition

14. Page 14 Niagara River – staging & over-wintering 1 st site in NA to receive “Globally significant IBA” designation Important over-winter feeding area for 100,000+ gulls (daily) 19 species have been recorded (14 spp. on a single day) Two species occur in globally significant numbers: 100,000 Bonaparte’s Gulls (20% world population) pass through annually; daily mean =10,000, maximum = 40,000 Herring Gulls – daily mean = 20,000, maximum = 50,000

15. Page 15 Niagara River – staging & overwintering Ring-billed Gull -- 18,000-27,000 individuals per day (fall / winter) Common Tern – 5,000+ individuals in Niagara Gorge during spring migration / staging Waterfowl – daily totals of 20,000 individuals of 20 species significant numbers of Canvasback, Common Merganser, Greater Scaup & Common Goldeneye

16. Page 16 0 0.2 0.4 0.6 LHLSCDRLENRLOSLR How important are rivers to maintaining GLs waterbird diversity? 6 5 7 7 Water body (upstream  downstream) Diversity / Richness * Shannon-Wiener Index (H’) 9 13 11

17. Page 17 % nests on connecting channels Connecting channels represent ~2% of the total area downstream of the St. Marys River How important are rivers to maintaining GLs waterbird diversity?

18. Page 18 Summary Most species are more numerous on US side of river; BCNHs the exception herons, terns and cormorants have increased since monitoring began; the two gulls show inverse-U pattern, but consistent with GLs-wide trends overall healthy waterbird community on Niagara River; status ‘improving’ overall Diversity lower on connecting channels than adjacent lakes Lowest on Detroit River, highest on SLR; NR had 2 nd highest diversity For most species, abundance is disproportionately higher on connecting channels than predicted by their area; rivers very important for some species NR has continental significance as an overwintering / migratory staging area for some species