Black Oystercatcher (Haematopus bachmani) foraging on varnish clams (Nuttallia obscurata) in Nanaimo, British Columbia

Emily Hollenberg 1 and Eric Demers2

1 406-­3905 Quadra St., Victoria, B.C., V8X 1J1; email:
2 Corresponding author: Biology Department, Vancouver Island University, 900 Fifth St., Nanaimo, B.C., V9R 5S5; email:

Abstract: In this study, we investigated whether Black Oystercatchers (Haematopus bachmani) feed on the recently intro­duced varnish clam (Nuttallia obscurata), and whether they selectively feed on specific size classes of varnish clams. Sur­ veys were conducted at Piper’s Lagoon and Departure Bay in Nanaimo, British Columbia, between October 2013 and February 2014. Foraging oystercatchers were observed, and the number and size of varnish clams consumed were recor­ ded. We also determined the density and size of varnish clams available at both sites using quadrats. Our results indicate that Black Oystercatchers consumed varnish clams at both sites, although feeding rates differed slightly between sites. We also found that oystercatchers consumed almost the full range of available clam sizes, with little evidence for size­selective foraging. We conclude that Black Oystercatchers can successfully exploit varnish clams and may obtain a significant part of their daily energy requirements from this non­native species.

Key Words: Black Oystercatcher, Haematopus bachmani, varnish clam, Nuttallia obscurata, foraging, Nanaimo.


PDFicon Hollenberg, E.J.R. and E. Demers. 2017. Black Oystercatcher (Haematopus bachmani) foraging on varnish clams (Nuttallia obscurata) in Nanaimo, British Columbia. British Columbia Birds 27:35–41. First published on­line October 2016.

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