Status and distribution of black rails in Virginia

OBJECTIVES:

The black rail is one of the most endangered bird species in Virginia and abundance and distribution information is essential to the development of an effective conservation strategy. The objectives of this project were 1) to determine the status and distribution of black rails in coastal Virginia and 2) to increase our understanding of the natural history of this species in the mid-Atlantic region.


PROJECT DESCRIPTION

Over the past 10-20 years, populations of black rails in Virginia and Maryland have declined more than 75% and are in eminent danger of extinction. There has been a reduction in both the number of breeding locations and a loss of individuals from historical strongholds. The reasons for this decline are not known. The status of the black rail in coastal Virginia had never been systematically determined. Information on the species existed only from anecdotal accounts and a small collection of unpublished historical records. Basic information on abundance and distribution is central to the development of an effective conservation strategy. We established and surveyed a network of 328 survey points throughout coastal Virginia within marshes containing historical occurrence records, and marshes with appropriate habitat. Surveys were conducted at night during the black rail breeding season in 2007 and 2008. Black rails were only detected at 12 survey points (< 4 % of total). All detections were restricted to the bayside marshes of Accomack County on the Delmarva Peninsula. No black rails were detected on the seaside of the Delmarva Peninsula, the western shore of the Chesapeake Bay, along the James –York-or-Nansemond rivers, or Back Bay. The location of all black rail detections shared 4 primary characteristics; 1) being within the high marsh zone, 2) near the upland edge, 3) within a zone of scattered Red Cedars or pines, 4) and only where the upland matrix was composed of a block of pine forest. Black Rails use the highest elevation areas of salt marshes composed primarily of a cover Salt-meadow hay, salt-grass, and black needlerush. Black rails appear to have disappeared completely from their historical distribution along the seaside of the Delmarva Peninsula. Moreover, known population strongholds at locations such as the Saxis Wildlife Management area have been dramatically reduced compared to past accounts. Black rails only occupy a small fraction of the available habitat. Overall populations appear to be dangerously low and may be at a risk of extirpation in the Commonwealth of Virginia. The future of this species is uncertain because black rails occupy habitats that are vulnerable to land-use change, in close proximity to upland nest predators, and sensitive to changes in climate and sea-level rise.


Years: 2007 – 2008

Status: Complete

CCB Staff: Mike Wilson, Bryan Watts, Fletcher Smith

Project Contact: Bryan Watts bdwatt@wm.edu (757) 221-2247