Fred L. Bunnell1,3, Arnold Moy1, Michael I. Preston2, Ralph W. Wells1
1Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, B.C. V6T 1Z4; email: Fred.Bunnell@ubc.ca
2Stantec, 2042 Mills Road Unit 11, Sidney BC V8L 5X4
Abstract: We evaluated predictions of birds’ response to climate for 32 bird species in British Columbia between the 1960s and 1990s. Of the 32 species tested, 20 showed expansion north when tested between 51° to 60° N, but expansion was significant for only seven. Four species remained south of 51° N in both decades. Ten spring and summer climate variables were evaluated; mean spring temperature was most informative. Temperature variables were highly correlated with other climate variables. Natural history attributes of species had major impacts on both range expansion and ability to project future ranges. Attributes having strong influences on range expansion included migratory behaviour, food type, breeding habitat and latitudinal distribution of the range prior to projection. As predicted, waterbirds showed the greatest tendency to expand ranges. Winter climate variables appear to have influenced those species showing southward shifts in range, apparently through shorter duration of ice cover. Estimated climate of the 1960s distribution was an inconsistent predictor of bird distribution during the 1990s.
Keywords: bird distribution, British Columbia, climate envelopes
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