2 Avocet and Stilt breeding status and population trends Gyug and Weir American Avocet and Blacknecked Stilt breeding status and population trends at Kelowna, British Columbia, 19972015 Les W. Gyug1 and Jason T. Weir2 1 Okanagan Wildlife Consulting, 3130 Ensign Way, West Kelowna, B.C. V4T 1T9
[email protected] 2 Dept. of Biological Sciences and Dept. of Ecology and Evolution, University of Toronto, 1265 Military Trail, Toronto, ON M1C 1A4
[email protected] Abstract: The American Avocet (Recurvirostra americana) is a rare and localized breeder in British Columbia with the single largest known B.C. colony in the remnant southern half of Alki Lake in Kelowna. From 1997–2015, up to 27 nests with eggs were observed in a single year, although in some years there appeared to be no successful nesting. Pulses in spring of high numbers of avocets at Alki and Robert lakes in Kelowna appeared to be partly from avocets heading further north in B.C. on their spring migration. High numbers of avocets only appear to remain in Kelowna for the breeding season if water levels in Alki Lake are suitable to isolate nesting islands. Spring first arrival dates of avocets to Kelowna have become significantly earlier by, on average, 11 days from 1997–2015. Egg laying dates in 1999–2000 ranged between April 25 and June 22, while hatching dates ranged between May 29 and July 20. Mean clutch size from 1997–2001 was 3.97 eggs per clutch. Nesting success in terms of broods hatching was 33% in 1999 and 60% in 2000.