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Response of Prothonotary Warblers to timber harvest and hydrology in a bottomland hardwood forest.
Cooper, Robert*,1, Gannon, Jill1, 1 School of Forest Resources, University of Georgia, Athens, GA, USA
ABSTRACT- The Prothonotary Warbler (Protonotaria citrea) is widely regarded as an indicator of the health of forested wetland ecosystems in the sotheastern United States. Bottomland forests in the lower Mississippi Alluvial Valley are threatened by deforestation and altered hydrology; those in public ownership often are actively managed by timber harvest. We investigated the effects of alternative timber harvest methods in bottomland forests of the White River National Wildlife Refuge, Arkansas, USA on the productivity of Prothonotary Warblers. Started in 1994, the study was a replicated, large-scale manipulative experiment with a before-after, controlled intervention design. Treatments (single tree selection, small patch cuts) reflected those used on the refuge and were designed to mimic natural disturbances. Treated plots had fewer territories on them, but nest success (probability of fledging at least one conspecific young) and productivity (fledglings produced per pair) was unaffected by timber harvest. Plot productivity (number of fledglings produced per plot) was less on treated plots than on control plots. Nest success showed significant annual variation primarily due, we believe, to annual variation in flooding. The major cause of nest failure was nest depredation by a variety of predators. Years with normal flooding resulted in higher nest success, and dry years, or dry periods within wet breeding seasons, resulted in increased nest depredation. We believe that in wet years, protection is afforded to nests built over water, and that alternative prey are available to primary nest predators. In dry periods, nests are relatively unprotected and alternative aquatic prey are not available to predators. Results suggest that: (1) the Prothonotary Warbler is a potentially useful indicator species for bottomland forest ecosystems, (2) active forest management is not a serious threat to Prothonotary Warblers in this system, and (3) proposed water management projects on the White River, which would affect hydrology, are a significant threat to this system.
Key words: Bottomland forest, forest management, Prothonotary Warbler, conservation