Written by Michael Wilson
June 16, 2008
The Appalachian Mountains of Virginia have long been considered population strongholds for Golden-winged Warblers (Vermivora chrysoptera) and Appalachian Bewick’s Wrens (Thryomanes bewickii altus). However, both of these species have undergone dramatic population declines in Virginia and throughout the greater Appalachian region including the general belief that Bewick’s Wrens are extirpated from this state. Reasons for the decline of these species may be many, but the most common explanations point to the loss and degradation of early successional breeding habitat. Golden-winged Warblers and Bewick’s Wrens use shrubby, early successional habitats for breeding such as idle vegetated areas, forest clear-cuts, alder swamps, utility right-of-ways (ROWs), and others. Several forces have worked together to cause the recent decline in early successional shrublands including direct losses caused by human development, re-forestation of farmland, fire suppression, and changes in agricultural and forestry practices. In addition, Golden-winged Warblers may be declining because of competition for breeding habitat and hybridization with Blue-winged Warblers. Blue-winged Warblers have been expanding their range eastward and into higher elevations that were once occupied exclusively by Golden-winged Warblers.
Distribution of Golden-winged Warblers, Blue-winged Warblers, and their hybrids in area of overlap in Virginia. Map by the Center for Conservation Biology.
A brood of osprey in Mobjack Bay showing a well-fed chick (left) and an emaciated chick (right). The chick on the right would die the following week due to starvation. Work in Mobjack Bay over a 40+ year period has shown that both reproductive rates and food delivery rates have declined dramatically. The decline in provisioning has led to an increase in brood reduction or chick loss due to starvation. Photo by Bryan Watts.