Avian communities of managed and unmanaged boreal forests.

Abstract

I compared the breeding bird communities of managed and unmanaged boreal forests in northeastern Minnesota. Birds were sampled in the spring and summer of 2010 and 2011 in the Superior National Forest (SNF, managed landscape) and Boundary Waters Canoe Area Wilderness (BWCAW, unmanaged landscape). Twelve point counts were completed along each of 10 paired transects for a total of 240 points, 120 points within each of the SNF and BWCAW. The total number of individuals detected per point was significantly higher within the BWCAW (F=9.76, p=0.01). Avian species richness per point was also significantly higher within the BWCAW (F=11.17, p<0.01). These results were negatively correlated with increased amounts of regenerating forests (mainly from logging) and positively correlated with tree species richness and canopy height of forest stands. Eight species were more common in the BWCAW compared with the SNF (black-capped chickadee (Poecile atricapillus), brown creeper (Certhia americana), Canada warbler (Cardellina canadensis), golden-crowned kinglet (Regulus satrapa), least flycatcher (Empidonax minimus), red-breasted nuthatch (Sitta canadensis), winter wren (Troglodytes hiemalis), and yellow-bellied flycatcher (Empidonax flaviventris)). Only the mourning warbler (Geothlypis philadelphia) and chipping Sparrow (Spizella passerina) were more common in the SNF. Species associated with mature or mixed forests tended to be found in the BWCAW at higher densities. In general, most species associated with early successional habitats did not differ between the BWCA and SNF landscapes. Results suggest that northern Minnesota forests with natural successional and disturbance regimes provide habitat for a higher density and richness of bird species.