Thin as a Rail

Why, since rails are widely distributed, are many of them absent from life lists of most birders? It is not because rails have especially sparse populations; six of the nine species breeding in North America are so abundant that hunting them is legal; only King, Yellow, and Black Rails are protected in the United States. Rather, many members of this family are so secretive that they move about unnoticed; when necessary, rails can melt into the marsh vegetation without causing much of a ripple. In situations where other marsh birds take flight and depart emitting harsh calls, rails often move silently. As Audubon wrote of the Clapper Rail in his Birds of America (1842):

On the least appearance of danger, they lower the head, stretch out the neck, and move off with incomparable speed, always in perfect silence ... they have a power of compressing their body to such a degree as frequently to force a passage between two stems so close that one could hardly believe it possible for them to squeeze themselves through.

Unlike highly visible, skittering shorebirds that run and pause in pursuit of the tide line, deliberate stepping, cryptically colored rails are usually hard to spot against their noncontrasting backgrounds. Indeed, rails may consider themselves invisible, for even on the rare occasion when they are in the open, they often act as though they cannot be seen. Such apparent indifference to discovery is sometimes mistaken for boldness, but more likely indicates that they do not recognize a human being 20 yards away as a potential threat. Even their fibrous, domed nests fade into the grass. Their generally elusive behavior causes difficulty for conservationists trying to census rail populations to learn enough about their ecology to implement effective management practices.

For seventy years mystery surrounded the calls of the rails and, for a while, their voices were misdescribed and misattributed. Since rails are rarely heard and more rarely seen, it remained difficult to positively identify the producer of a call until the use of tape recordings to attract the bird became practical. Many rails limit calling to the breeding season, often awaiting the break of day or onset of darkness. Besides the infrequent acoustic advertisements, telltale evidence of rails consists of little more than their tracks, pelleted remains of meals, and inch-sized white splatters of droppings.

Rail disappearing acts also work in water. They can readily submerge their normally buoyant bodies, dive when pressed, and speed their paddling by using wings underwater. So effectively do they maintain a low profile that their main nonhuman predators are pike, black bass, and other predatory fish which feed on their young.

Not only do rails usually elude their predators, they seem to delude their prey. During a tail-jerk display a rail's tail is cocked upward and its head (which usually bobs as it steps) is frozen still. This posture is thought by some to permit a steady view of the foraging area while misleading small prey to mistake its tail for its head.

Many birders hope to spot rails at dawn or dusk low tides when the birds reputedly come forth to bathe and preen at the water's edge or to forage on temporarily exposed mud-dwelling prey. Other enthusiasts venture to marshlands when very high tides compress the amount of space and covering vegetation available to both rails and stalk-climbing snails that rails eat. Along the Atlantic coast, hunters of Clapper Rails (Marsh Hens) usually await the first full-moon tide of September. When this tide is pumped by a north wind, which forces the water level exceptionally high and pushes the birds to even higher ground, it is known as Marsh Hen Tide.

Rails are subject to periodic calamities; floods destroy nests and young, and during their nighttime migrations, heavy fog can take them off course, even into cities. In 1977 a storm brought an early freeze and reduced by two-thirds the breeding success of Clapper Rails in New Jersey. In 1940 one hurricane left an estimated 15,000 of these rails dead in South Carolina, and in 1976 another storm killed some 20,000 in New Jersey.

Ironically, the remarkable ability of rails to reestablish after natural disasters could lead to their demise, for their ability to respond to nature's inconstancy may promote false confidence in marshland managers who assume rails will recover from human interference with equal success. Pollution in salt-marsh habitats cannot necessarily be counterbalanced by the apparent physical hardiness of rails. In Georgia, for example, 95 percent of rails tested in one area near an industrial plant had unacceptably high concentrations of mercury in their muscles -- levels high enough to make eating them ill-advised. It would not be surprising if searching for these furtive creatures proves ever more frustrating. The disappearance of a rail seen ambling amid the marsh grasses may be illusory, but the disappearance of high-quality rail habitat is not.

SEE: American Coots; Metallic Poisons.

Copyright ® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.