The Eastern Black Rail (Laterallus jamaicensis jamaicensis) is one of the most elusive and threatened birds in North America. This small, mouse-sized rail inhabits dense marsh vegetation and is rarely seen, due to its secretive nature. Experts estimate there are less than 250 calling males left in the wild, making the Eastern Black Rail one of the most endangered birds in the contiguous United States. However, confirming exact population numbers has proven extremely challenging. This article will examine what is known about the remaining Eastern Black Rail population, why the population has declined so severely, and what conservation efforts are underway to save this critically endangered bird.
Estimating the Eastern Black Rail Population
The Eastern Black Rail is extremely difficult to detect, even for experienced birders and researchers. The bird blends into marsh vegetation and rarely flies. Its primary call is a quiet “kicker” call, only given by males and hard to hear over moderate distances. Nocturnal habits make the rails even harder to survey. These factors combine to make estimating the population exceptionally difficult. Here is what is known:
Breeding Bird Survey
The North American Breeding Bird Survey provides long-term population data by enlisting volunteer birders to conduct annual counts along roadside survey routes during the breeding season. However, this survey is ineffective for rails which occupy wetland areas away from roads. Only 1-2 Eastern Black Rails have been detected during the history of the Breeding Bird Survey.
Call-response Surveys
Targeted Eastern Black Rail surveys involve playing recordings of “kicker” calls to elicit responses from rails at wetland sites during the breeding season. However, call-response rates are highly variable (0-90% response rates). Surveys conducted from 2010-2018 by the Atlantic Coast Joint Venture estimated approximately 250 responding males left but with wide credibility intervals of 100-1,700 males, illustrating the large uncertainty.
Environmental DNA
A 2018 study detected Eastern Black Rail DNA at just 11 of 489 wetland sites surveyed along the Atlantic and Gulf coasts. Though not a direct measure of population size, this finding suggests an sparse and highly dispersed distribution. More eDNA surveys combined with occupancy estimation models may improve population estimates.
Challenges
The Eastern Black Rails’ secretive habits, uneven distribution, and habitat within inaccessible marshes make population estimation very difficult. The lack of sightings prevent even a reliable estimate of population trends over time. More extensive surveys using call-response and environmental DNA sampling would improve knowledge but marsh access issues remain challenging. Better population monitoring methods are critically needed.
Reasons for Population Decline
The Eastern Black Rail has declined precipitously since the late 1800s and dramatically in recent decades. The causes are not fully clear but likely include:
Habitat Loss
Draining and development of marshlands for agriculture, roads, and urban areas has caused substantial habitat loss, especially on the Atlantic Coast. For example, 75% of coastal marshes have been lost in Connecticut.
Habitat Alteration
Modification of wetland hydrology and invasive plant species have degraded remaining marsh habitat quality. The rails require wetlands with very dense, wet vegetation up to a foot tall.
Predation
Increasing populations of predators like raccoons, foxes, and birds of prey may contribute to declining rail numbers. Predator control around occupied sites has shown an increase in rails.
Sea Level Rise
Rising oceans are projected to inundate and alter wetlands along the Atlantic Coast, threatening the loss of remaining habitat. Marshes may be able to accumulate sediment and migrate inland to compensate depending on topography.
Climate Change
In addition to sea level rise impacts, climate change may affect rails by altering humidity, increasing droughts, changing vegetation, and encouraging predators. These effects remain speculative but concerning.
| Year | Estimated Population |
|---|---|
| Late 1800s | Abundant |
| 1990s | 2,000 calling males |
| 2009 | 400-1,200 calling males |
| 2018 | Less than 250 calling males |
Conservation Efforts
Many groups are working to better understand and protect the vanishing Eastern Black Rail:
Surveys
Targeted call-response surveys by federal agencies and nonprofits aim to improve population monitoring and distribution information. Survey results inform habitat protection priorities.
Habitat Protection
Land acquisition and conservation easements seek to protect occupied and suitable wetlands from destruction or incompatible uses. Hydrology restoration can improve habitat quality.
Predator Management
Predator exclosures, trapping, and hunting restrictions around priority sites may help reduce nest predation rates and increase rail productivity.
Captive Breeding
A new captive breeding program launched in 2019 aims to establish a captive population as an insurance policy against extinction. Offspring may later be released to bolster wild populations.
Listing Under Endangered Species Act
Listing as Threatened or Endangered would provide legal protections and enable additional conservation funding and efforts for the Eastern Black Rail. A listing decision is expected in 2023.
Conclusion
The Eastern Black Rail’s population has plummeted to an estimated 250 calling males or fewer based on recent surveys, though uncertainty remains high. Habitat loss, degradation, predators, and climate change threats have likely contributed to the declines. Improved monitoring and urgent habitat protection and management will be critical to prevent the extinction of this highly imperiled bird. While the population is at a crisis point, targeted conservation action offers some hope of stabilizing and recovering the Eastern Black Rail population if implemented quickly and robustly. The fate of this secretive bird ultimately depends on society’s willingness to prioritize and fund habitat and species conservation efforts.
