BREEDING BIRD COMMUNITIES OF THE WESTERN AND NORTHERN CANADIAN BOREALFOREST - RELATIONSHIP TO FOREST TYPE

We examined the distribution of 80 species of breeding birds across 67 census plots from a variety of sources in the boreal forest of wester n and northern Canada to obtain information on bird habitat associatio ns for forest management. The sites ranged from upland black spruce (P icea mariana) to riverine deciduous forests and wet, marshy bogs. Axis 1 of an ordination (detrended correspondence analysis) demonstrated a gradient in bird communities from dry to wet sites; axis 2 may have b een a black spruce (nutrient poor) to mixed deciduous forest gradient (nutrient rich). Hierarchical classification (TWINSPAN) identified fiv e groups of sites according to their bird communities. Despite geograp hical variation in bird communities and possible geographical variatio n in habitat associations, sites were classified according to their fo rest types rather than regional affinities. Yellow-rumped warblers (De ndroica coronata) and dark-eyed juncos (Junco hyemalis) showed a prono unced gradient of increased abundance from deciduous to coniferous sit es. White-throated sparrows (Zonotrichia albicollis) and alder flycatc hers (Empidonax alnorum) showed a reverse gradient. In 22 sites of kno wn-age aspen (Populus tremuloides) - mixedwood forests from central Sa skatchewan, an ordination indicated a strong relationship between stan d age (and thus the proportion of coniferous cover) and bird community structure. The highest combined densities of Neotropical migrants occ urred in old forests, whereas short-distance migrants were most abunda nt in young forests. The highest abundance of upper-canopy gleaners wa s found in old forests, whereas ground foragers were most abundant in early successional forests. These findings have important implications for management of boreal forests.