Black Rail Life History

Habitat

Habitat Marshes

Black Rails nest in marshes and wet meadows across North America, including riparian marshes, coastal prairies, saltmarshes, and impounded wetlands. All of its habitats have stable shallow water, usually just 1.2 inches deep at most. On the Atlantic and Gulf coasts, Black Rails nest in the higher, drier parts of marshes, where tidal activity is least and where different types of grasses, sedges, and rushes occur in mosaic-like patches. Key plant species in these habitats include saltmeadow hay, sand cordgrass, chairmaker’s bulrush, saltgrass, needlerush species (genus Juncus), and various species of pickleweed (genus Salicornia). Areas of saltmarsh cordgrass are often adjacent to these habitats but receive too much tidal activity for Black Rails to utilize for nesting, though the birds do sometimes forage in lower, wetter parts of the marsh. In California, American glasswort, various bulrush (Scirpus) species, and the alkali seaheath are key plants for Black Rails. These plants, especially taller patches of seaheath at the marsh margins, may provide cover for the rails during periods of high tides. Away from tidal habitats, Black Rails nest in a variety of wet meadows, marsh edges (including along creeks and rivers), around farm ponds, and even in hayfields with standing water. Migrating birds and wintering birds select habitats with the same characteristics as breeding habitats, but some occur in dry rice fields, among other rail species, as well.

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Food

Food Aquatic invertebrates

Black Rails eat mostly small invertebrates as well as seeds of aquatic plants. They forage in shallow portions of marshes (usually with under an inch of water), walking among plants to glean insects and other invertebrates from the ground, the water, or the vegetation. They sometimes feed in deeper parts of marshes, often under cover such as high-tide wrack (dead vegetation situated like a canopy on top of living marsh grasses). Among their prey items are diving beetles, weevils, earwigs, woodlice (sowbugs or “roly-polies”), grasshoppers, ants, snails, and spiders. They also consume small amounts of plant matter, including seeds of bulrushes and cattails. Despite its habit of calling during the night, this species probably feeds mostly during the day, by sight.

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Nesting

Nest Placement

Nest Ground

Males and females may select the nest site together. Marsh nests are set on or close to the ground, at the base of taller vegetation such as needlerush or bulrush, where the ground is moist (sometimes near water up to an inch deep). Some nests are concealed by layers of dead or living vegetation as well.

Nest Description

A circular bowl woven of fine grasses, rushes, and sedges, often at the base of tall sedges that provide partial cover, with a ramp of dead vegetation on one side. Nests average 5 inches across and 3 inches tall (taller if the parents add to it during high tides), with an interior cup 3 inches across and 1.7 inches deep.

Nesting Facts

Clutch Size:4-13 eggs
Number of Broods:1-2 broods
Egg Length:1.0-1.1 in (2.44-2.81 cm)
Egg Width:0.7-0.8 in (1.89-2.04 cm)
Incubation Period:17-20 days
Egg Description:

Creamy white with fine brown spots.

Condition at Hatching:

Covered with black down, leave nest within one day. Fed by parents.

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Behavior

Behavior Probing

Black Rails are difficult to study, as most of their activity is hidden from view inside dense marsh grasses. From late winter through spring, males establish and defend territories up to about 10 acres in extent. In some areas, males sing their unusual song throughout the day and night, while in other places, they sing mostly at night, shifting from one part of the territory to the next over the course of the evening. Males in conflict make low growls. Most studies suggest that Black Rails are monogamous in their mating system. Their courtship behavior is unknown. Both parents remain active near the nest, sharing incubation duties, and both often shepherd the tiny chicks after hatching. Males in particular defend the nest area vigorously, charging at intruders with rattling, open wings and open bill, hissing, and making other aggressive calls. Black Rails are small birds that make easy prey for marsh hunters like Great Blue Herons, Great Egrets, Northern Harriers, and owls. Fish Crows and gulls have also taken Black Rails. Mammals like raccoons, foxes, and cats presumably also eat Black Rails or their eggs, as do snakes. The rails are especially vulnerable to predators when flooded out of their preferred habitats.

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Conservation

Conservation Red Watch List

Black Rail populations are difficult to estimate, but well-studied populations along the Atlantic coast north of South Carolina are in steep decline, and many historical populations in the United States have declined or disappeared. Partners in Flight estimates a global breeding population of 52,000 and rates the species a 17 out of 20 in the Continental Concern Score, placing it on the Red Watch List, the group’s highest level of concern. Black Rail is listed as Endangered or Threatened in six eastern states, Arizona, and California. The most recent estimates of populations in eastern North America (from Texas to the Atlantic coast) suggest as few as 455 breeding pairs may remain. Because Black Rails require such shallow water, they are highly susceptible to changes in water levels, whether from climate change (extremes of drought and deluge), water diversion for agriculture, or the draining of wetlands for mosquito control. They are not often shot by rail hunters but are sometimes caught in mammal traps set in marshes. Like other nocturnal migrants, Black Rails sometimes collide with structures such as communication towers or tall buildings. Potential negative effects of pesticide use (e.g., for mosquito control), burning or grazing of marshes, destruction of upland marsh habitats, or sea-level rise on this species have not been studied in detail.

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Credits

Eddleman, William R., R. E. Flores and M. Legare. (1994). Black Rail (Laterallus jamaicensis), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Flores, R. E. and W. R. Eddleman. (1991). Ecology of the California Black Rail in southwestern Arizona. Yuma, AZ: Yuma Proj. Off. and Arizona Dept. Game & Fish.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Watts, Bryan D. (2016). Status and distribution of the eastern black rail along the Atlantic and Gulf Coasts of North America. The Center for Conservation Biology Technical Report Series, CCBTR-16-09. College of William and Mary/Virginia Commonwealth University, Williamsburg, VA.

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