SONGBIRD POPULATION DECLINES

Every year since 1966, thousands of volunteers have assisted wildlife biologists in conducting the annual North American Breeding Bird Survey (BBS), which is organized and managed by the USGS Patuxent Wildlife Research Center. Each volunteer surveys a 25-mile roadside circuit by stopping for three minutes every one-half mile and counting all birds that are seen or heard. These surveys provide wildlife biologists with valuable trends for many of our bird populations. Many of these populations, especially those species that migrate from the tropics to North America each year, have declined significantly throughout their range from the 1960s to 1990s. These songbird declines have been associated with fragmentation of eastern forest habitat into isolated patches, loss of wintering habitat in Central and South America, loss or significant alternation of optimum breeding habitat, increased predation related to habitat alternation, and nest parasitism by the Brown-headed Cowbird, scientific name: Molothrus ater. Visit the website of USGS North American Breeding Survey or view bird abundance maps from the Migratory Bird Data Center.

Scientists rank the eastern deciduous and coniferous forests as the first and second most important breeding habitats for migratory songbirds in North America. Within the southeastern United States, wildlife biologists have documented population declines and ranked a number of migratory songbirds and their habitats as species or habitats of special concern. Birds of the forest understory or shrub-scrub species (nest in the shrub layer) that ranked high as species of special concern are birds that commonly overwinter in shrubby habitat (young successional habitat) in the tropics and therefore would not be adversely affected by cutting of the tropical forest, which creates shrubby habitat.

One of these species, the Painted Bunting, scientific name: Passerina ciris, ranks high for need of attention in important coastal areas of the southeastern United States. Unlike declining populations of forest interior migratory birds that need large areas of unbroken forests, the Painted Bunting depends on young shrub and grassland habitat for breeding and nesting primarily in upland maritime shrub-scrub habitat of the South Atlantic Coastal Plain from North Carolina to northeastern Florida. Painted Buntings can also use shrub-scrub habitat in open pine and maritime oak forests. This upland coastal habitat on barrier islands and coastal mainland is highly vulnerable to loss from development.   Habitat loss alone, however, may not be the cause of an annual population decline of >3.5% (1966-1987) for the bunting. Actual causes for decline are unknown, but may include degradation or loss of breeding habitat, nest parasitism by the Brown-headed Cowbird, changes in climate, or increased predation in breeding habitat that could be related to warmer weather or habitat alteration.

Recently wildlife biologists in Georgia have completed studies that provide some important information on Painted Bunting survival and habitat use. Although not all the answers have been found to restore the Painted Bunting population to levels of the 1960s, it is clear that many management practices can be modified or initiated to enhance the population of this declining species. We hope that the information and recommendations provided will not only stimulate interest in the recovery of the Painted Bunting, but also become a stepping stone to many other conservation issues in our coastal wildlife habitats.