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Clapper Rail

Amelia Grider, Greenville, Alabama
The clapper rail (Rallus crepitans) is a medium-sized marsh bird, roughly the same size as a chicken when it is fully grown. It was given its scientific name by Johann Friedrich Gmelin in 1789 but had been generally described as a member of the genus Rallus by John Latham in 1785. These elusive birds, known as the "ghosts of the marsh," are found in tidal salt marshes, areas consisting mainly of marsh grass and mud flats. They are hard to find, because they do not walk around in the open unless they are looking for food. They are more likely to be heard than seen. In Alabama, they are found only in Baldwin and Mobile Counties but are common in similar habitats throughout the United States. They are considered of moderate conservation concern in the state because of habitat loss along coastal marshlands. Clapper rails are closely related to all members of the genus Rallus but are geographically closest to the king rail. King rails are larger than clapper rails and are more reddish with a rusty red-orange face. Also, king rails are more commonly found in freshwater, rather than saltwater, marshes in the interior United States.
Clapper rails are habitat specialists and will only be found in areas with an abundance of desirable vegetation and food sources. Habitat specialists are organisms that live in only one type of habitat and cannot survive anywhere else. In Alabama, they may be found along the Alabama Coastal Birding Trail wherever salt marshes occur and on either side of Mobile Bay. Weeks Bay, Dauphin Island, and Fort Morgan are all good public areas for finding clapper rails. These birds feed primarily on fiddler crabs and other small crustaceans but will also consume insects, mollusks, and seeds. They in turn are predated upon by many different animals, such as birds of prey, snakes, alligators, and various mammals. Clapper rails also function as hosts for several aquatic parasites that are dependent upon the rails to spread their eggs.
Adult coloration is highly variable, ranging from a light gray-brown to darker browns and grays that can appear black. These differences in plumage coloration are normally based on geographic distribution. Individuals inhabiting the Gulf Coast of the United States are noticeably lighter in color, with predominantly light brown plumage, than their counterparts on the eastern coast and have lighter markings on the side of the head between the eye and the beak. Birds in both regions display such variations as gray faces, red eyes, and a distinct black-and-white alternating pattern on the rear abdomen. All clapper rails have long legs for wading that may range from orange to light gray. Several members of the genus Rallus are characterized by their long, slightly down-curved beaks, which may be orange, yellow, pink, or gray based on age and geographic distribution. Males and females do not differ in coloring. Unlike their parents, clapper rail chicks are covered in downy black feathers, with black legs, toes, and beaks. They can be distinguished from the black rail (Laterallus jamaicensis) by their eye color, which is dark rather than red. Juvenile clapper rails have less patterning on the body and appear more muted in color than adults, with a distinctly whiter abdomen and more gray feathering. They have an average wingspan of 19 inches (48.3 centimeters). Males are typically much larger than females, a characteristic known as sexual dimorphism, with males having 20 percent greater body mass than females on average. Specific dimensions of the separate sexes are not readily available, but both male and female clapper rails range from 12.6 to 16.1 inches (32 to 41 centimeters) in length, with males on the higher end and females on the lower end. The birds average around 10 ounces (290 grams).
Little is known about the courtship behaviors of clapper rails, but scientists believe that males and females perform duets that include a clapping call (hence their name) and courtship displays to attract mates. Other shorebirds are known to use similar methods. When seeking mates, males make distinct calls that are typically fast, loud, repeating keks. Females will produce a call as well, but theirs is a ket-ket-kar. These birds form monogamous pairs, with each bird only breeding with one mate at a time. The beginning of the mating season varies by region, with most pairs forming between the months of March and April. The exact period of breeding for Alabama is currently unknown but is believed to begin in late March and continue through mid-May, when the first eggs are laid. The exact reproductive age of adults is not known, but it is likely that most birds are sexually mature at one year of age.
Clapper rails prefer nesting within coastal salt marshes as well as some freshwater marshes. Nests, constructed by the males, are located on elevated platforms that sit above the high-tide mark to keep the eggs from being washed away. The location, near the edges of large areas of marsh grass, protects them from predators and also provides easy access to the mudflats on which they forage. The nests are made primarily of dead marsh grass fronds placed on the ground or elevated on top of living grass fronds. Oftentimes, these nests have ramps, entrance holes, and covers to hide them from predators. Clapper rail eggs are a creamy white color with small, irregular brown spots scattered across the surface. Clutch size normally ranges from 4-12 eggs and both males and females will take turns incubating them until they hatch. Chicks will remain with the parents for roughly 5-6 weeks before fledging and venturing out on their own.
Clapper rails are threatened in many ways, from both natural and human causes. Increase in hurricane intensity and frequency and rising water levels, caused by climate change, are threats to nests. Adults, chicks, and eggs all face predation, and introduction of invasive non-native animals, such as dogs, cats, and exotic snakes, is known to have serious negative impacts on rail populations. Removal of these organisms is crucial to increasing the survival rate of eggs and chicks. Additionally, these birds are listed as game birds in the state of Alabama and therefore may be hunted. Clapper rails have a higher tolerance for pollutants compared to other shorebirds, but exposure to increased concentrations of pollutants can lead to reproductive problems. These birds are not listed as federally endangered, but the Alabama Natural Heritage Program has designated them as imperiled within the state, meaning there are few sightings. The biggest threat to clapper rails is habitat degradation and destruction. Because they require specialized habitat, decreases in wetland areas pose a grave threat to them. Therefore, protection and conservation of marshes and restoration of wetlands are the first major steps in helping clapper rail populations flourish in Alabama.

Additional Resources

Eddleman, W. R., et al. "Conservation of North American Rallids." Wilson Bulletin 100(3): 458-75.
Rush, Scott A., et al. "Clapper Rail (Rallus crepitans)." In The Birds of North America, edited by Paul G. Rodewald. Ithaca, N.Y.: Cornell Lab of Ornithology, 2012.
Published:  November 1, 2017   |   Last updated:  November 1, 2017