Table 3 — Guild density (pairs per 100 acres) of breeding birds on logged and unlogged study plots, west-central Idaho, 1975 to 1979 



Density 



Unlogged Prelogging Postlogging' 



Guild 



1975 



1976 



1977 



1978 



1979 



1975 



1976 



1977 



1978 



1979 



Feeding 























Foliage feeders-gleaners 



111.1 



1 01 n 

 1 ^1 U 



1 HQ Q 



1 uy.o 



1 O 1 o 



1 Uo.o 



1 07 Q 

 1 O/ O 



1 (^7 O 

 iOf d 



1 C3 T 

 1 DO. O 



1 dA Q 



1 CQ R 



1 bo.o 



Aerial-sally feeders 



1 O 7 



1 O. / 





on n 



1 7 1^ 



ICO 



Q 1 O 



ot^ n 



OQ 7 



Q 1 O 



o 1 



O 1 O 

 Old 



Timber drillers 



C 



C..D 





O.U 





O.U 



1 O 



1 .d 



O.U 





d.O 



c: 

 d.O 



Timber gleaners 



O 1 o 



1 7 C 



O 1 o 



07 C 



07 A 



OQ 7 



do, / 



OO 7 



1 7 



1 /.O 



1 c o 



dd.O 



Ground gleaners 



46.2 



53.7 



56.2 



33.7 



41.2 



42.4 



47.5 



59.9 



67.3 



55.0 



Nesting 























Conifer tree nesters 



36.2 



49.9 



37.5 



27.5 



23.7 



46.2 



57.4 



53.6 



58.6 



51.2 



Conifer-deciduous tree nesters 



42.5 



33.7 



36.2 



43.7 



36.1 



51.2 



49.9 



58.6 



63.7 



60.0 



Bush and small tree nesters 



54.9 



68.7 



66.1 



62.5 



67.4 



69.8 



71.2 



73.6 



83.6 



103.6 



Primary cavity nesters 



6.2 



5.0 



7.5 



5.0 



7.5 



2.4 



7.5 



5.0 



3.7 



5.0 



Secondary cavity nesters 



34.9 



35.0 



39.9 



42.5 



47.4 



41.2 



38.7 



32.5 



28.7 



31.2 



Ground nesters 



20.0 



22.4 



25.0 



21.2 



21.2 



30.0 



33.7 



43.6 



43.7 



28,7 



'Logging t>egan in September and was completed in October 1976. 



Among the six nesting guilds represented, only the 

 secondary cavity nesters reacted negatively to logging 

 (table 3). Numerically, cavity-nesting species made up 

 22 percent of the breeding bird community on the un- 

 logged plots compared to 15 percent on the logged plot. 

 Primary cavity nesters had similar densities on both 

 logged and unlogged plots. There was a tendency toward 

 increases in bush and small tree nesters, especially evi- 

 dent in the second and third years after logging. 



RESULTS: SMALL MAMMALS 



Nine species of small mammals were trapped during 

 the 5-year study (table 2). Deer mice, yellow pine chip- 

 munks, and boreal redback voles accounted for 93 percent 

 of the 815 individual animals trapped. Each of those 

 species was trapped each year on both logged and un- 

 logged plots. No shrews were caught in the logged forest. 

 Western jumping mice were trapped only in the logged 

 watershed. Other species, including the northern flying 

 squirrel, longtail weasel, northern pocket gopher, and 

 water vole, were trapped irregularly and in smaller num- 

 bers. There were large differences in the number of small 

 mammals trapped each year in both the logged and un- 

 logged forest. 



Deer mouse populations fluctuated irregularly during 

 the study (fig. 1). Estimated densities in the unlogged 

 forest ranged from 0.2 to 5.0 animals per acre. Annual 

 fluctuations were less pronounced in the logged water- 

 shed. Deer mouse populations were similar on both 

 logged and unlogged plots during the postlogging period. 

 A different pattern of response is suggested when trap- 

 ping results are expressed as the mean number of 

 individual animals trapped per year in prelogging and 

 postlogging environments (table 2). Significantly fewer 

 individual deer mice were trapf)ed on the logged plot 

 during the postlogging period. 



Studies conducted elsewhere in the West found differ- 

 ent patterns of response. Gashwiler (1970), Halvorson 

 (1982), Hooven and Black (1976), Tevis (1956), and 

 Van Horne (1981) found more deer mice on logged areas 

 when compared with nearby unlogged habitats. Yet 

 others reported either similar or higher deer mouse popu- 

 lations in uncut forests when compared with recently 

 logged areas (Harris 1968; Petticrew and Sadleir 1974; 

 Scott and others 1982; Sullivan 1979). Differences in the 

 effect of logging may be partly a result of differences in 

 the amount of cover remaining on logged areas as well as 

 variations in food availability characteristic of early suc- 

 cessional stages (Van Horne 1981). 



Yellow pine chipmunk populations on the logged area 

 were larger than those of the uncut forest (fig. 1). Logging 

 resulted in a nearly twofold increase in estimated density, 

 reaching a high of 4.1 animals per acre in the second year 

 following logging. The number of individual chipmunks 

 trapped showed a significant pattern of positive response 

 to the timber harvest (table 2). It was the most commonly 

 trapped small mammal in the logged forest. The yellow 

 pine chipmunk is an adaptable species, occupying a vari- 

 ety of forested habitats and a wide range of successional 

 stages (Thomas 1979). It is particularly abundant in open 

 stands of ponderosa pine and Douglas-fir (Rickard 1960). 



Annual fluctuations in redback vole populations were 

 less extreme than those of the deer mouse and yellow pine 

 chipmunk (fig. 1). Estimated densities in the unlogged 

 forest ranged from 0.7 to 2.0 animals per acre. Popula- 

 tions on the logged plot were only slightly higher than 

 those on the unlogged plot. No significant difference was 

 found in the number of individual redback voles trapped 

 in the cut and uncut forest (table 2). Conversely, redback 

 voles were not found on a nearby plot when the slash was 

 burned following diameter-cut logging (Medin 1986). 

 Scott and others (1982) reported little difference in the 



7 



