Courtesy Kenn Kaufman
Along North America's Atlantic and Gulf coasts, the Clapper Rail is a permanent resident from about New Jersey southward into Tamaulipas, Mexico, including the islands of the western Caribbean. A disjunct population occupies most of the Yucatan Peninsula's coast. On the west coast the distribution is patchy, and it resides from San Francisco Bay southward through Baja California to Nayarit. A population also resides in the Lower Colorado River valley, including the Salton Sea. A small population of migratory Clapper Rails extends from northern New Jersey into southern New England.
Of the approximately 21 recognized subspecies of Clapper Rail, the 3 that are Endangered are in the West. The California Clapper Rail (R. l. obsoletes) occurs in the San Francisco Bay area. Its range has shrunk dramatically in the last 120 years. The Light-footed Clapper Rail (R. l. levipus) ranges in southern California from about San Quentin Bay to Baja California Sur. The Yuma Clapper Rail (R. l. yumanensis) lives along the Lower Colorado River and its adjacent marshes, southward to San Blas, Nayarit, along the Mexican Pacific coast.
In summer, this rail inhabits salt marshes with open water and uses the wetter parts, where open water and plants mix. Typical plants in this situation include cordgrass, pickleweed, mangrove, and needlerush. Thick vegetation at the edge of the marsh may be important when the water is high. Emergent and barely submerged plants facilitate travel, provide some cover, and harbor prey. In Arizona, the Yuma Clapper Rail uses wetlands with emergent plants like bulrush, cattail, and sedge. Generally avoiding ice and very cold water, wintering rails may shift into more dense vegetation, higher parts of the marsh, or more mature plants.
With an omnivorous diet, the Clapper Rail eats what it can find and swallow. Locating prey by sight and perhaps by smell, it picks items from new plant growth, the ground, and floating vegetation. It may also poke into mud or dead vegetation, but not deeply. The diet includes crabs, shrimp, insects, marine worms, the seeds of water plants, mussels, clams, and snails.
Males are territorial year round but are most aggressive during the breeding season and will chase off any other vocalizing male. The pairs form monogamous bonds that appear to last for the season. The male calls the female with a series of "keks," that sound like stones being tapped together. He courts her with exaggerated postures that feature the flash of his white under tail coverts. Using course marsh plants, the pair raises a platform from just a few inches to 5 feet above the water or ground. Set among thick marsh vegetation, the nest may have a cover and an access ramp. Several other mounds are constructed as roost sites for the chicks.
5-8 whitish eggs, splotched with shades of brown, are incubated by the pair for about 20 days. Covered in black down, the chicks are soon able to walk and swim, but need warmth from the adults. When threatened, they may hide or be carried to safety by an adult. In about a week, the adults split the brood and care for their own portion, until the young reach independence at about 6 weeks old. The pair may raise a second brood.
Only the Atlantic population from New England south into the mid-coast of North Carolina makes a traditional migration. Spring migrants probably move in March and April, but the precise schedule and their routes have not been determined. Fall migrants begin to depart in late summer and continue to move well into November. Rails breeding farther north migrate earlier. Migration occurs at night and probably at low altitudes.