Territory quality and reproductive success of Black Oystercatchers in British Columbia

Abstract

I investigated the relationship between the physical characteristics of breeding territories and the reproductive success of Black Oystercatchers (Haematopus bachmani) in British Columbia. I compared measures of the threat of egg and brood depredation, conspecific competition, and food supply with measures of reproductive success on 38 oystercatcher breeding territories during 1996 and 1997. Oystercatchers breeding on territories near Glaucous-winged Gull (Larus glaucescens) colonies had smaller first clutches than pairs free of neighboring gulls. Oystercatcher pairs hatched and consequently produced more young on shallow sloping intertidal shoreline sites compared to steep-sloped islets and shorelines.