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Effects of Timber Harvests on Invertebrate Biomass and Avian Nest Success

Concerns over declining songbird populations have led to investigations of effects of various timber management practices on breeding songbirds. We assessed the influence of 2 types of practices, two-age and clearcutting, on invertebrate biomass and avian daily nest survival in the Monongahela Natio...

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Bibliographic Details
Published in:Wildlife Society bulletin 2000, Vol.28 (4), p.1123-1131
Main Authors: Duguay, Jeffrey P., Wood, Petra Bohall, Miller, Gary W.
Format: Article
Language:English
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Summary:Concerns over declining songbird populations have led to investigations of effects of various timber management practices on breeding songbirds. We assessed the influence of 2 types of practices, two-age and clearcutting, on invertebrate biomass and avian daily nest survival in the Monongahela National Forest of West Virginia during summers of 1995 and 1996. We also examined relationships between invertebrate biomass, avian daily nest survival, and wood thrush (Hylocichla mustelina) nestling growth rates. Mean total invertebrate biomass collected per sample day and litter-dwelling invertebrates collected per sample day were 0.0614 g and 0.0254 g greater (P≤0.10), respectively, in the unharvested than clearcut treatment late in the season (2 Jun to 12 Jul) when most birds had young in the nest; whereas invertebrates that hide under tree bark during the day had greatest biomass (P=0.003) in the two-age treatment during this same time period (0.1355 g greater than clearcut and 0.0616 g greater than unharvested). In addition, daily nest survival rates (216 nests) were greater in the unharvested than two-age treatment (P≤0.05). The lesser daily nest survival rates of birds breeding in the harvested treatments may be due to increased predator activity within these areas and/or reduced food supplies. Significant positive correlations between invertebrate biomass and daily nest survival rates of breeding birds and faster growth rates of wood thrush nestlings in stands with a greater invertebrate biomass suggest that changes in invertebrate biomass caused by silvicultural practices have an influence on breeding birds within these areas.
ISSN:0091-7648
1938-5463