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Colonial Waterbirds Nesting on the Niagara River, 1976-2011.

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

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Colonial Waterbirds Nesting on the Niagara River, 1976-2011.

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  1. Colonial Waterbirds Nesting on the Niagara River, 1976-2011. Dave Moore1 Francie Cuthbert2 Chip Weseloh1 Linda Wires2 1Canadian Wildlife Service 2University of Minnesota Niagara River RAP Implementation Committee Session 10 Apr. 2013 Niagara College, Niagara-on-the-Lake, ON

  2. The Great Lakes Bi-national Decadal Colonial Waterbird Survey • 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

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

  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 & CaspianTerns • 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. Niagara River – colony distribution Lake Ontario Canada USA Niagara River Lake Erie

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

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

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

  9. Niagara River – abundance & trends Great Egret 5 * 1 Nests *17 nests at 2 sites in Canada in 2012 1 0 0

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

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

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

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

  14. Niagara River – staging & over-wintering • 1st 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. 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. How important are rivers to maintaining GLs waterbird diversity? 0.6 Diversity / Richness 13 11 0.4 Shannon-Wiener Index (H’) 9 7 0.2 * 7 6 5 0 LH LSC DR LE NR LO SLR Water body (upstream  downstream)

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

  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 2nd 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

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