657-202 Street, Langley, B.C., V2Z 1V7
Abstract: During 1998–2002, I visited 22 locations in the Lower Mainland where Western Screech-Owls (Megascops kennicottii) were known to occur. I visited each location five or more times and used playback tapes to attract screech-owls. There were positive responses from five locations during the first portion of the study, but by the end of the study, I concluded that screech-owls had disappeared from all 22 locations. Christmas Bird Count data from 1988 to 2004 indicate that on Vancouver Island, screech-owl numbers declined at an average annual rate of 17% while those in the Lower Mainland declined at an average annual rate of 32%. Screech-owls declined earlier for those Christmas Bird Counts which showed an earlier increase in Barred Owls (Strix varia) and for those which showed the greatest final number of Barred Owls (i.e. post-invasion). By combining my data with those of Robertson et al. (2000), I found that screech-owls were detected more often in fragments of forest that were smaller than approximately 20 ha. I therefore concluded that screech-owls were rapidly disappearing from the Lower Mainland and that the likely causes were predation by Barred Owls, in conjunction with increased competition for cavities and habitat loss.
Key words: Western Screech-Owl, Megascops kennicottii, Barred Owl, Strix varia, predation, population decline, habitat, competition
© Unless copyright restrictions are indicated, any paper, note or review (or excerpts from them) may be reproduced in another publication provided that both the author(s) and British Columbia Birds are credited fully.