No evidence of short-term effects of clear-cutting on artificial nest predation in boreal mixedwood forests

Abstract

We examined whether nest predation in unharvested blocks of trembling aspen (Populus tremuloides Michx.) would increase when adjacent stands were clearcut in the boreal mixedwood forest of Alberta, in 1993, 1994, and 1998. Artificial nests placed on the ground and in shrubs were baited with Chinese painted quail (Coturnix chinensis L.) and plasticine eggs, which along with cameras, were used to identify nest predators. Fragmented sites were isolated from continuous forest by clear-cutting in 1994, while control sites remained unfragmented. Overall, predation on ground and shrub nests did not increase in isolated forest patches post-harvest (p = 0.056 and p = 0.085, respectively), nor was there a consistent effect of distance from a clearcut edge (p >= 0.050). Predation on ground nests was higher in 1994 and 1998 compared with 1993 levels (p < 0.001), while predation on shrub nests remained relatively constant over the 3 years (p >= 0.073). Mice, voles, and red squirrels (Tamiasciurus hudsonicus Erxleben) were the main identified predators of ground and shrub nests, respectively. Probability of nest predation could not be consistently predicted by nest site vegetation or adjacent land cover, but was related to predator abundance. However, neither predators nor songbirds congregate at recent clearcut-forest edges, and we conclude that elevated nest predation caused by clear-cutting may not occur in the boreal mixedwood, at least not at current levels of harvest and within 5 years of clear-cutting.