FIRST OCCURRENCE OF THE CAVE SWALLOW IN BRITISH COLUMBIA

摘要

On 11 November 2012 we observed a group of four swallows foraging over a freshwater pond at lona Island Regional Park in Richmond, British Columbia (49° 21' N 123。21' W). At a distance of 100 m,we quickly identified three of them as Barn Swallows (Hirundo rustica), while the fourth appeared at first to be a Cliff Swallow (Petrochelidon pyrrhonota). When it got closer to the observers, we identified the fourth bird-by its dark cinnamon-orange forehead, pale cinnamon-orange throat and chin, and dark cinnamon-orange rump-as a Cave Swallow (Petrochelidon fulυa） (Figures 1 and 2), a species previously unknown in British Columbia. The bird remained at lona Island for nine days (to 19 November), during which period it was seen and photographed by many. Photographs show that the bird was undergoing primary molt and that it had replaced primaries 1 through 6 (Figure 1). The prebasic molt of adult Cave Swallows begins promptly after breeding, with flight feathers being replaced from June through September. In contrast, the preformative molt of immature birds occurs later, in the fall and winter, with flight-feather replacement from September through March (Pyle 1997). Given the date of our observation and the extent of primary replacement, we aged the bird as an immature in preformative molt.