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Ecology of mature-forest and early-successional-shrubland birds in managed temperate deciduous forests
We investigated whether group-selection provides habitat of similar quality for early-successional shrubland-nesting birds as does clearcutting. There was no difference in avian reproductive success between clearcuts and groupcuts, indicating that clearcuts and groupcuts provide habitat of similar quality for early-successional shrubland-nesting birds. We studied Chestnut-sided Warblers (Dendroica pensylvanica) nesting in 29 patches of regenerating northern hardwoods forest 0.15–0.69 ha in area to determine whether the ecology of this species is affected by patch size or shape. Chestnut-sided Warbler density was higher, and pairs initiated nesting later in smaller patches, yet patch size was unrelated to fledging success or nest predation rates and patch area. Territory density, nest initiation dates, fledging success and nest predation rates were unrelated to patch shape. We compared nest predation rates between groupcut and clearcut borders (0–5 m from edges) and forest interior areas (45–50 m from edges) using artificial shrub nests baited with Zebra Finch (Taeniopygia guttata) eggs. The probability of a nest being depredated was higher in edge areas than forest interior areas (P = 0.02) and was independent of nest concealment, nest height, or whether the nest was adjacent to a clearcut or a groupcut (P = 0.18). We compared survival rates of used natural nests baited with House Sparrow (Passer domesticus) eggs with survival rates of active bird nests at the same sites. Survival rates of artificial nests (27.7%) were significantly lower than nest survival rates of natural nests (58.6%). We suggest that lack of parental defense is a contributing factor responsible for higher predation rates on artificial nests, and is likely to be a potential confounding factor in future nest predation experiments using artificial nests. We studied patterns of plumage variation in the Chestnut-sided Warbler to determine if plumage brightness was related to reproductive performance. There were no relationships between plumage brightness and reproductive success of either male or female Chestnut-sided Warblers. Adult males and females were brighter than subadult males and females, however, adult and subadult males and females fledged as many young as adult males and females. Thus, delayed plumage maturation in the Chestnut-sided Warbler is not associated with decreased reproductive output in subadult birds. We suggest that the duller plumage of subadult Chestnut-sided Warblers is more likely a reliable indicator of subordinate status, and that delayed plumage maturation serves in this species to reduce aggression from adult birds.
King, David Ian, "Ecology of mature-forest and early-successional-shrubland birds in managed temperate deciduous forests" (1999). Doctoral Dissertations Available from Proquest. AAI9932321.