the elimination ot these competing species, or possi- 

 l)ly the cliaiige in climatic conditions, makes other 

 s|)ecies more abundant. This is especially noticeable 

 among birds — the red-breasted nuthatch, brown 

 creeper, winter wren, golden-crowned kinglet, soli- 

 tary vireo, black-throated green warbler, black- 

 i)urnian warbler, Canada warbler, and slate-colored 

 jiinco attaining much larger populations in the 

 Smoky Mountains of Tennessee than in northern 

 Ontario. In addition the veery, black-throated blue 

 warbler, and often black and white warblers become 

 numerous. This constitutes a variation in the boreal 

 forest biociation (Stewart and Aldrich 1952) which 

 may be designated the Appalachian jaciation. 



\Mien hemlock, which reaches its best develop- 

 ment in the Appalachian Mountains, and spruce-fir 

 forests occur in the same region, some bird species 

 adaptable to both show a definite preference for one 

 over the other. In Table 23-1 it is evident that the 

 red-breasted nuthatch, brown creeper, winter wren, 

 veery, golden-crowned kinglet, and slate-colored 

 junco prefer the spruce-fir forest, while the black- 

 capped chickadee, possibh' the solitary vireo, black- 

 throated blue warbler, black-throated green warbler, 

 blackburnian warbler, and Canada warbler prefer 

 hemlock forests. A similar differentiation of bird 

 populations in these two forests is also evident in 



FIG. 23-2 Species common in 

 the coniferous forest biome: 

 (a) porcupine, (b) gray jay, 

 (e) moose, boreal forest, (d) 

 wapiti, western forest (courtesy 

 U.S. Forest Service). 



Algonquin Provincial Park in southern Ontario 

 (Alartin 1960). This may be a reflection of the dif- 

 ference in paleo-ecological history of hemlock and 

 spruce-fir forests. The long association of hemlock 

 with deciduous forest may also have permitted the 

 invasion into the former of the Acadian flycatcher, 

 wood thrush, ovenbird, and scarlet tanager. 



Spruce-fir forests occur at higher elevations in 

 the mountains, and in some areas at least, as in the 

 Catskill Mountains of New York, a zone of deciduous 

 forest intervenes the hemlock and spruce-fir forests. 

 Elsewhere, as in the Cheat Mountains of West Vir- 

 ginia (Brooks 1943), the two coniferous forests come 

 into direct contact. Apparently because of the close 

 interrelations between hemlock and the northern 



Coniferous forest, woodland, and chaparral biomes 305 



