Impact of an ice storm on resident bird populations in eastern North America

Abstract

The January 1998 ice storm was very dramatic, particularly in Québec, with five days of nearly non-stop freezing rain and temperatures below 0 °C. We compared results of Christmas Bird Counts (complete counts conducted during one day within a 12-km radius by volunteers in winter) conducted before (1997–1998) and after (1999) the storm in control areas (16 sites) and in affected areas (15 sites). Abundance ratios (after/before) were significantly higher in control versus affected sites for Rock Dove Columba livia, Mourning Dove Zenaida macroura, Hairy Woodpecker Picoides villosus, Blue Jay Cyanocitta cristata, Black-Capped Chickadee Parus atricapillus and House Sparrow Passer domesticus. Paired -t- tests also indicated that the abundance of Brown Creeper Certhia americana and Downy Woodpecker Picoides pubescens was lower in affected sites following the storm. Only European Starling Sturnus vulgaris abundance increased significantly in affected sites. Species found in open habitats that forage mostly on the ground were less affected by the storm than tree foragers were. The effect of the storm on bird populations was quite significant and increased frequency of such storms could have drastic consequences on bird populations in the long term. Key words: ice storm, birds, Christmas Bird Counts, winter survival, climate change