Code

CCBTR-98-03

Publication Date

1998

Abstract

Reported declines of neotropical migratory songbird populations have drawn the attention of the scientific community and the general public. Much of this concern has been focused on the loss of breeding and winter habitat. However, each year during the spring and fall, these species migrate thousands of kilometers along major movement corridors known as flyways. In order to successfully complete migration, birds must make periodic stops in flyway habitats to replenish energy reserves. Changes in the availability of these stop-over habitats may contribute to population declines. One of the most important migration corridors for bird species that breed throughout northeastern North America is the Atlantic Flyway. Each year millions of birds migrate along the coastal fringe and utilize habitats for refueling. Coastal habitats such as those used by migrants are experiencing some of the highest development pressures of any within North America. Because of the high concentration of military installations within the Atlantic Flyway, U.S. Department of Defense (DOD) lands represent one of the most promising opportunities to manage lands for the benefit of migrant songbirds. Through its partnership with the Partners in Flight initiative, DOD has committed to integrate neotropical migratory bird management efforts into existing natural resource management programs that are consistent with the military mission. This project was initiated to 1) investigate the diversity and abundance of migrants using forested habitats within the Little Creek Naval Amphibious Base in Norfolk, Virginia, and 2) to investigate habitat use patterns for the purpose of making management recommendations. Birds were sampled throughout the peak of fall migration in 1995 and 1996. A banding station was operated for over 8,700 net-hours resulting in the capture of 1,600 individuals of 66 species. A total of 480 point counts were conducted during the fall of 1996, resulting in the detection of 2,800 individuals of 71 species. Finally, a total of 14,907 seconds of foraging data was collected on 3 representative species of neotropical migrants (including Black-throated-blue Warbler, Black-and-white Warbler, and Ovenbird). Habitat type was shown to have a significant influence on the use of forest patches by neotropical migrants. Capture rates were several times higher in live oak and deciduous patches compared to pine. Similarly, survey data show that both species richness and migrant abundance were significantly higher in deciduous patches when compared to pine. In addition, both species richness and overall abundance were positively and significantly influenced by the presence of understory vegetation. For all 3 species observed, foraging success was 2-3 times higher in deciduous when compared to pine stands. The results of this study provide insights into the habitat requirements of land bird migrants that are important to the development of appropriate land management strategies. The most significant finding in this regard is that forested habitats are not equal with respect to migration habitat. Specific Management Recommendations include: 1. Maintain existing forested habitat. 2. Protect existing deciduous and live oak forest. 3. Promote and maintain understory vegetation.

Topic

Abundance/distribution; Biodiversity/Community Structure; Migration

Species

Neotropical migrants

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