Local-Scale Association of Boreal Birds with Clearcuts Does Not Translate to the Landscape Scale

Abstract

Many boreal forest birds, including the Common Nighthawk and Eastern Whip-poor-will, have shown recent steep population declines. Both species are known to use clearcuts as habitat locally; however this relationship has not been tested at a landscape-scale. In this study I addressed the question: Are landscapes with more clearcut associated with higher occupancy of Common Nighthawk and Eastern Whip-poor-will? I selected 49 recent clearcuts (≤ 15 years old) of similar size and placed acoustic recorders on their edges. I measured the proportion of recent clearcut within multiple spatial extents around each bird sample site. I also measured the proportion of open wetland in the landscapes as a covariate. Occurrence of neither species was significantly affected by the proportion of clearcut in the surrounding landscape, at any of the tested spatial extents. However, Common Nighthawk occupancy was lower in landscapes with higher proportions of older (11-15years old) clearcuts, and for both species occupancy was higher in landscapes with higher proportions of open wetland, significantly so for Eastern Whippoor-will. I propose that these species nest on clearcut edges because they seem to be similar to other open habitat like wetland edges. However, clearcuts may not offer the same level of insect prey supply as offered in the open wetlands and therefore do not act as similar foraging habitat. Thus, clearcut edges may act as ecological traps, attracting birds to nest in areas of lower habitat quality. I demonstrated that local-scale habitat associations do not necessarily scale up to a landscape-scale. My results suggest that the conservation of open wetlands will be important for persistence of these boreal bird species. iv