Concern about declining populations of many songbirds of mature forest interiors has fueled opposition to even-aged management on public lands. However, recent work has documented the presence of such birds in regenerating clearcuts in the post-breeding period, a critical time in avian life cycles.  Whether such habitat shifts are commonplace, and whether birds’ habitat choices produce detectable differences in physiological condition, remains unclear.  I used constant-effort mist-netting in mature and young regenerating forests in northwestern Pennsylvania from  July to September of 2005 to 2008 to test (1) whether forest-interior birds used early successional habitats disproportionally in the post-breeding season, and (2) whether such use affected physiological condition.

Results/Conclusions

Capture rates for forest interior species were significantly higher in early successional (12.4/100 net-hrs) than forest interior (5.3/100net-hrs) habitats, although ratios differed among species.  Further, birds captured in early successional habitats were more likely to have fat deposits (P = 0.05) and less likely to have ectoparasites (P<0.001) than birds caught in forest interiors, suggesting that use of such habitats carry significant fitness benefits.  I found no differences in either of two Body Condition Indices, however.  I suggest that early successional habitats created by even-aged forest management may provide an important resource for many late-successional forest birds, although there may be compensatory costs to such choices that I did not measure in this study.