Assessment of Black Rail Status in North Carolina, Breeding Season 2017 and 2018 Summaries
Abstract
The Black Rail (Laterallus jamaicensis) is the most secretive and least understood marsh bird in North America with the Eastern Black Rail (L. j. jamaicensis), one of two subspecies that occur here, listed as endangered in six states along the Atlantic Coast and proposed for federal listing under the Endangered Species Act (USFWS–R4–ES–2018–0057, 2018). Black Rails require dense vegetation for cover during all stages of their life cycle. They require wetlands with minimal water coverage during the breeding season. Historic population size for the Eastern subspecies was likely in the tens of thousands (25,000 to 100,000; Delaney and Scott 2002) but is now believed to be in the hundreds to low thousands. Eastern Black Rails breed within three geographic areas within North America including the Atlantic Coast, the Gulf Coast, and the Midwest. The Atlantic Coast has generally been thought to support the largest breeding population throughout the range with pairs mostly confined to the highest elevations within tidal salt marshes. The historic breeding range along the Atlantic Coast has contracted more than 450 kilometers south and the population is estimated to be declining by 9% annually (Watts 2016). The primary driver of declines over the past three decades is believed to be sea-level rise and associated tidal inundation during the nesting season. North Carolina has long been recognized as a stronghold for Black Rails within the mid-Atlantic region. Most of what we know about the distribution and abundance of Black Rails in the state is based on site specific surveys and scattered anecdotal records (Fussell and McCrimmon 1976, Fussell and Wilson 1983, Davis et al. 1988, Collazo et al. 1990, LeGrand 1993, Fussell 1994, Paxton and Watts 2002, Watts 2016). These reports have documented a number of tidal marsh breeding locations, a well-known larger population at the Cedar Island National Wildlife Refuge, and at Piney Island military installation (both in Carteret County). In the late 1800s and early 1900s Black Rails were documented in the western part of the state using agricultural fields but there have not been consistent records since that time (Lee 1999, Watts 2016). Prior to 2014, a comprehensive status assessment for Black Rails in North Carolina had not been conducted, nor were there any existing systematic monitoring programs in place to assess the health of Black Rail populations. The purpose of this project is to gain a systematic view of the distribution of Black Rails in coastal North Carolina to help determine their status and distribution, to expand upon previous survey locations from the 2014 and 2015 field seasons, to determine if Black Rails continue to occupy historic strongholds, and to initiate an inland survey centered on agricultural lands with high density freshwater wetlands, farm ponds, Carolina Bays, and other water features that Black Rails have historically used within the region. We designed a broad survey frame so sampling locations could be used for monitoring purposes into the future. During the 2017 field season, 284 coastal points were surveyed, and during the 2018 field season 192 points were surveyed. All points surveyed in 2017 were along the outer coast in tidal or impounded wetlands. During the 2018 survey, 169 inland points and 23 coastal points were surveyed. The 2018 coastal survey locations were comprised of a network of previously occupied areas from year 2000 on. Three rounds of surveys were conducted between 18 April and 20 July 2017 and between 1 May and 15 July 2018. All points were surveyed three times unless there were access issues during one of the survey rounds. We conducted a total of 1,394 individual play-back surveys, 844 in 2017 and 550 in 2018. We detected a minimum of 9 individual Black Rails at 4 survey points in 2017 and we detected zero Black Rails in 2018 for survey occupancy of .01% (4 of 476 total survey points). During the 2014 and 2015 breeding seasons, a total of 262 points were surveyed for the presence of black rails within the outer Coastal Plain. Rails were detected within 20 points (7.6%) including an estimated 22 individuals at those points. We found no new potential breeding areas during the 2017 survey effort, and detected zero Black Rails during the 2018 survey season.
