Secretive marsh birds named for a scraping cry
Rails of family Rallidae are cosmopolitan ground birds from twelve to sixty-three centimeters and twenty grams to three kilograms. Sexual plumage rarely differs; bills range from clapper-rail spears to stubby cones. Their English name scrapes from French râle—echoing a harsh call rooted in Latin radere, to scrape.
The family Rallidae, first named by the French polymath Constantine Rafinesque in 1815, spans the tiny Swinhoe's rail of East Asia up to birds weighing three kilograms, and takes in crakes, coots and gallinules. The AviList catalogue recognises 148 species in 38 genera. In the Old World, long-billed kinds tend to be called rails and short-billed ones crakes, while North Americans say rail regardless of bill. Bills are the family's most variable trait: longer than the head in the American clapper rail, broad in coots, massive in purple gallinules, and some coots and gallinules sport a fleshy frontal shield. Only a couple of species, such as the watercock and little crake, show obvious differences between the sexes.
Most are shy, hard-to-see birds with strong legs and long toes suited to soft, uneven ground, living in dense damp vegetation near lakes, swamps and rivers, especially reed beds. They are largely omnivorous, eating invertebrates, fruit and shoots, and their loud calls, some whistling, some barely birdlike, carry through thick cover and darkness. Nesting habits are poorly known; most clutches hold five to ten eggs, though one to fifteen have been recorded.
Short, rounded wings give weak but durable flight, and migrants travel at night. Because they are easily blown off course, rails often end up as vagrants and have reached remote islands. There, with no mammals to flee, many abandoned flight: 31 of roughly 150 known species evolved flightlessness independently, a textbook case of parallel evolution. Rails already carry small flight muscles, just 12 to 17 percent of body mass, so shedding them saves energy quickly, and the change happens far more often on tropical islands, where no seasonal migration is needed.
That flightlessness proved fatal when people and their animals arrived. As humans settled Melanesia, Polynesia and Micronesia, an estimated 750 to 1,800 bird species vanished, about half of them rails. The Wake Island rail was eaten to extinction by a starving Japanese garrison during the Second World War.
Source: Rail (bird)
