Re-Survey and Population Status Update of the Black Rail in Virginia
The Black Rail is the most imperiled bird species along the Atlantic Coast. This species is undergoing a conservation crisis that without emergency management intervention may be extirpated from many portions of its Atlantic Coast range in our lifetime. Black Rails have undergone significant reduction in it breeding range, loss of breeding sites in the core stronghold of its population, and has a dim future in the face of sea-level rise and other disturbances. The objective of this study was to provide an update of the population status of Black Rails in Virginia. We conducted a previous study for Black Rails in 2007 that marked the first time that a systematic survey of the species was conducted in the Commonwealth. Results of that survey effort showed that Black Rails were only detected in 10 of 212 survey points located on the Delmarva Peninsula and were completely absent from 40 additional survey locations on the western shore of the Chesapeake Bay. Based on the low detection rates, and apparent population decline from earlier decades, a re-survey of the lower Delmarva Peninsula was considered critical to provide current trends and distribution. We conducted surveys for Black Rail in 2014 on Virginia’s eastern shore (i.e., the lower Delmarva Peninsula) by selecting all 12 survey points with positive occurrences in the 2007 survey effort, 114 survey points that were a subset of locations without Black Rail occurrences from the 2007 survey, and a selection of 9 new points never before surveyed on the Chincoteague National Wildlife Refuge (total points surveyed = 134). Black Rails were only detected at 2 survey locations. Both of these detections were of single birds from the Saxis Wildlife Management Area. Black rails were absent from 10 other survey locations where they were detected in 2007. Population numbers of the Black Rail in Virginia has reached an all-time low in Virginia. Traditional strongholds such as the Saxis WMA have held more than 20 Black Rails as recent as the 1990s have become significantly reduced. Reasons for the decline of Black Rails are not completely understood but are likely a result of a combination of factors that degrade or remove their required habitat, disrupt breeding productivity, or lower survival. High marsh habitats that Black Rails rely upon are particularly vulnerable to loss and transformation as a result of sea-level rise and receive high visitation by nest predators that can disrupt breeding. Overall, the dramatic population loss of Black Rails in the Mid-Atlantic provides indication that the ecosystem they rely on is no longer suitable. Emergency management actions are required to prevent further population loss and begin restoration. A critical management need for the Black Rail is to create and manage habitats that are not influenced by sea-level rise. Artificial habitats such as managed impoundments offer the best opportunity to fit these demands. Impoundments could be placed inland to avoid rising seas and could be fenced to reduce predator visitation. A broad strategy and site-specific recommendations for managing impoundments to benefit Black Rails are still in need of development through experimentation. We recommend continual monitoring of the Black Rail population in Virginia into the future using the same protocol as 2007 and this 2014 study. Monitoring of Saxis WMA should occur annually and the remaining survey locations should be visited every 4 to 5 years. Survey points with no rail detections from 2007 and not surveyed in 2014 should be rotated into future survey designs to be assess whether or not birds are not moving in the landscape between monitoring benchmarks.