Breeding Birds, Logged Forest 



Breeding bird density ranged from 172 to 209 pairs 

 per 100 acres (40.5 ha) on logged study plots; 23 to 27 

 species were territorial (table 2). The most common 

 species, each making up more than 5 percent of the 

 breeding bird population, were: 



chipping sparrow 

 dark-eyed junco 

 Empidonax flycatcher 

 western tanager 

 Other common species were: 

 Cassin's finch 

 MacGillivray's warbler 

 American robin 

 solitary vireo 

 calliope hummingbird 

 yellow-rumped warbler 

 red-breasted nuthatch 

 Swainson's thrush 



Those 12 species accounted for 76 percent of the 

 breeding bird community. 



In standing crop biomass, the American robin was the 

 leading species followed by the dark-eyed junco, 

 northern flicker, western tanager, chipping sparrow, 

 hairy woodpecker, and Cassin's finch. Those seven 

 species made up 62 percent of the standing crop biomass 

 in the logged forest. Total standing crop biomass on 

 logged plots ranged from 76 to 105 grams per acre (189 

 to 259 grams per ha). 



Hole-nesting species accounted for 16 percent of the 

 breeding bird density on logged plots compared to the 

 22 percent found on unlogged plots. Most of the 

 difference in hole-nester density resulted from reduced 

 abundance of the red-breasted nuthatch, mountain 

 chickadee, and brown creeper on logged areas. The hairy 

 woodpecker, northern flicker, and white-breasted 

 nuthatch had similar densities on both logged and 

 unlogged plots. 



Species richness was generally lowest on unlogged 

 plots and highest on logged plots (table 2). When 

 compared with the unlogged control plot, annual bird 

 species richness values trended consistently upward on 

 the logged areas. Year-to-year variation in the number of 

 territorial species on the unlogged control plot was 

 slight. The evenness (equitability) component of species 

 diversity tended to decline each year in postlogging 

 environments. No consistent annual trend in species 

 evenness was noted on the unlogged control plot. No 

 clear patterns were apparent between years or between 

 logged and unlogged plots with respect to bird species 

 diversity. 



Species Responses 



Although breeding bird density and standing crop 

 biomass totals in the unlogged and logged forest were 

 similar, there were important changes in the composition 

 of the bird community on logged plots (table 2). 



Twenty-five species established territories on unlogged 

 plots during the study; 34 species were territorial on 

 logged plots. 



Ten of the breeding bird species found in the logged 

 forest were not present before logging; these included 

 the house wren, mountain bluebird, western bluebird, 

 black-backed woodpecker, yellow-bellied sapsucker, 

 olive-sided flycatcher, warbling vireo, and black-headed 

 grosbeak. All of the newly territorial species attracted to 

 logged areas occurred in low densities. Among the spe- 

 cies that were territorial in the unlogged forest, only the 

 golden-crowned kinglet was absent from logged study 

 plots. 



In addition to those species attracted to logged plots, 

 several others appeared to react positively to structural 

 changes in the vegetation caused by timber cutting. Spe- 

 cies with higher densities after logging included the 

 Empidonax flycatcher, Townsend's solitaire, American 

 robin, chipping sparrow, dark-eyed junco, and Cassin's 

 finch. Of these, only the Cassin's finch nested in the 

 overstory; the others nested either on the ground or in 

 the understory layer (Medin 1985). Each of the six spe- 

 cies or genera have been classified by Thomas (1979) as 

 having medium or high versatility ratings with respect 

 to reproductive and feeding orientation. All but the 

 Empidonax flycatcher are characteristic of ecotonal 

 habitats. The American robin, chipping sparrow, dark- 

 eyed junco, Cassin's finch, and Empidonax flycatcher 

 are widespread breeding species in the coniferous forests 

 of central Idaho. 



Seven species responded negatively to the logging. 

 These were: 



mountain chickadee 

 red-breasted nuthatch 

 brown creeper 

 Swainson's thrush 

 Townsend's warbler 

 MacGillivray's warbler 

 western tanager 



Three species— the mountain chickadee, red-breasted 

 nuthatch, and brown creeper— are secondary cavity 

 nesters. All but the MacGillivray's warbler are found in 

 old-growth habitats (Thomas 1979). The brown creeper 

 nests under loose bark and is often associated with 

 mature stands of ponderosa pine. The Townsend's war- 

 bler is a species characteristic of multiple canopy, 

 mature, and old-growth true fir and mixed conifer 

 stands. 



Densities of other breeding bird species listed in table 

 2 were similar on both logged and unlogged plots. The 

 most numerous of these included the calliope humming- 

 bird, hairy woodpecker, northern flicker, hermit thrush, 

 solitary vireo, Nashville warbler, yellow-rumped warbler, 

 and pine siskin. Incongruently, three of these species— 

 the hairy woodpecker, hermit thrush, and Nashville 

 warbler— were given low versatility scores by Thomas 

 (1979). 



Five woodpecker species (yellow-bellied sapsucker, 

 hairy woodpecker, white-headed woodpecker, black- 

 backed woodpecker, and northern flicker) were territorial 

 on one or both of the logged plots during the study 



7 



