Searching for North America’s Most Secretive Bird—The Black Rail
The Eastern Black Rail, a subspecies of the Black Rail, is a white whale to many bird enthusiasts due to its elusive nature. Rarely seen in flight, it acts more like a mouse than a bird, shuffling underneath thick marsh vegetation. It is also crepuscular, meaning it is mainly active in the hours of dawn and dusk.
Despite challenges in detecting this secretive bird, surveys indicate severe population declines across its range over the past 20 years resulted in the Eastern Black Rail being listed as threatened under the Endangered Species Act in 2020. The Eastern Black Rail may also be one of the first birds listed with climate change as the primary threat.
About the size of a sparrow, Black Rails are the smallest rail species in North America. They are mainly gray to black and have chestnut backs with white speckling that have been poetically referred to as a constellation. Perhaps most notable are their bright red eyes. Their most common territorial call is an excited ‘kickeedo,’ but they also produce aggressive growl sounds and other calls to communicate.
Eastern Black Rails occur along the Gulf Coast states, inhabiting coastal prairies, saltmarshes, and impounded wetlands. Although they occur in both coastal and inland settings, the majority of records come from the coast. The high marshes the birds inhabit are infrequently inundated by water and are nestled between the dry uplands and the regularly flooded low marshes. High marshes are dominated by species of cordgrass, needlerush, and saltgrass. In addition to habitat loss and fragmentation, on an elevational scale, high marsh faces threats from both below and above.
An example of coastal high marsh, dominated by saltmeadow cordgrass and desert saltgrass. Photo by Heather Levy.
Fire suppression allows for woody encroachment from the uplands, and on the other end, climate change is driving sea level rise, causing low marshes to push further into the high marsh. For Black Rails, microtopography is a key element, allowing for some areas of shallow water that provide foraging habitat. They have a narrow niche and require appropriate water levels, vegetation structure, and vegetation composition in order to persist.
Since 2020, the Tall Timbers Stoddard Bird Lab became involved in a NOAA RESTORE Science Act project assessing occupancy of Black Rails, and the influence of prescribed fire on high marsh habitats suitable for Black Rails across the Gulf Coast states. This project, nicknamed Firebird, has over 15 partnering entities and is the largest to focus on Eastern Black Rails across a huge swath of their range. Key questions of the fire component include determining which burn interval provides the most suitable vegetation composition and structure in high marshes. We have also partnered with the Geospatial Lab here at Tall Timbers to create burn severity maps that assess the influence of habitat patchiness and vegetation composition on the intensity of prescribed fire. In addition, we are sampling areas outside of the experimental fire regimes to determine regional occupancy and habitat use.
Last breeding season (March– July) was a pilot season to determine the most productive survey techniques and to identify areas within the panhandle that support Black Rails. We surveyed for breeding birds at 147 public sites from Franklin to Pasco counties across state parks (Florida Department of Environmental Production lands), national wildlife refuges (US Fish and Wildlife Service lands), and wildlife management areas (Florida Fish & Wildlife Conservation Commission lands). Of the 147 sites visited, 15% were occupied by Black Rails. If a site was occupied, there was a 20% chance of detecting it during any given visit. We generally detected more birds in the morning surveys than those in the evening, but this was not statistically different. Peak detection occurred in May and June.
The breeding season fieldwork is currently in full swing, and we’re detecting several more birds this year than we did last year during the same time. After experience from a full field season last year, the reasons are likely due to a few things—better understanding of their habitat, and observers that are more familiar with some of the obscure vocalizations these birds make. But most importantly, it’s likely also a product of desirable habitat structure from prescribed burns applied in the past two years. Many of the sites where we’re detecting birds are now between 1-3 years post-burn.
In addition to conducting call-broadcast surveys, we are also testing the utility of acoustic recording units (ARUs) to detect Black Rails by partnering with researchers from the K. Lisa Yang Center for Conservation Bioacoustics, housed within the Cornell Lab of Ornithology. We are working to help train their algorithm by providing data and manually reviewing processed output. ARUs can be set out in the marsh to record continuously, or during pre-selected times throughout the day for weeks at a time, depending on the make and model. They have become popular in the secretive marshbird world, but there are still a lot of questions that need to be answered before ARUs can be implemented effectively for long-term and large-scale Black Rail monitoring.
A portion of the Black Rail population in the Gulf Coast are short-distant migrants, but the ratio of migratory to resident birds is unknown, as are potential differences in their overwintering and breeding microhabitat. To answer these questions, we sample for birds over the winter using a slightly more tactile approach. Several nights a week crews of 4-8 go out in the evening outfitted with a 15-meter-long rope and spotlights. After sunset, the crew lines up along the rope and walks it slowly across pre-determined transect lines, hoping to flush birds. When a bird is located, a handheld net is then gently placed over the bird. We caught several rails this winter; a single aluminum band was placed on each bird in case it is re-captured in the future. Once captured, we take general morphometric measurements in addition to fecal and feather samples. Fecal and feather samples are shipped off to a collaborator for processing to investigate diet and stable isotope analyses that inform us which birds are migratory. Very little is known about overwintering ecology and behavior, so we were intrigued when at one site we flushed two females and a male at the same spot, and at another location we had a female/male pair together on two separate occasions.
Both winter and breeding season are accompanied by vegetation monitoring in areas where we’ve detected rails, and areas randomly chosen around where we are sampling for birds. The method involves classifying habitat type, and assessing species composition and vegetation thickness at the height where the vegetation is growing, in addition to vegetation thickness a few centimeters off the ground.
Heather Hill (left) and Heather Levy (right) measure vegetation thickness with a marked PVC pole. Photo by Destinee Story Braden
From a bird’s eye view (well, if you’re a bird that flies), the grasses that dominate these marshes appear too thick for birds to easily move through, but if you look closely underneath and peel back the grasses, many of them grow in bunches and provide railways for small animals. Quantifying these characteristics will also help inform the proper fire regime, in addition to identifying potentially suitable areas for rails where presence is not known.
Throughout the project, in addition to monitoring occupancy, we’ve developed questions we hope to answer for Florida in the coming years, such as home range size, microhabitat structure for both breeding and overwintering birds, and movement ecology. Despite the unique challenges associated with studying such elusive creatures, we’re hopeful the information we’re gathering will feed directly into conservation and management plans with a goal of habitat and monitoring improvements across the coastal range of the Eastern Black Rail.
