Rails

Many species of rails that live on remote, oceanic islands have become flightless, because of the lack of natural predators. This is true of various endemic species that are specific to particular islands (that is, they do not occur anywhere else), and also of flightless populations of more wide-ranging species of rails. The benefit of flightlessness to rails living on islands is not totally clear, but some ornithologists have speculated that this trait might have something to do with the conservation of energy, coupled with an absence of predators.

Unfortunately, flightless rails are extremely vulnerable to suffering debilitating population declines when humans introduce predators to their isolated habitats. Most commonly, these catastrophes involve accidental introductions of rats, or deliberate introductions of pigs or cats. At least 15 endemic species of island rails are known to have become extinct, largely as a result of introduced predators. Numerous other island rails still survive, but are endangered.

However, the real number of extinctions is undoubtedly much larger than this. Some ornithologists have speculated that each of the approximately 800 islands inhabited by Polynesians in the Pacific Ocean may have had one or several endemic species in the rail family, as well as other unique species of birds. Most of these rare and endemic species became extinct in prehistoric times, soon after the islands were discovered and colonized by prehistoric Polynesians. These extinctions occurred as a result of predation by introduced rats, over-hunting by humans, and to a lesser degree, losses of habitat.

Various species in the rail family have been hunted more recently for meat or sport. Today, however, this is a less common practice than it used to be. Some species of gallinules are sometimes considered to be pests of aquatic crops, such as rice, and they may be hunted to reduce that sort of agricultural damage. However, this is a relatively unusual circumstance.

Because rails are generally species of wetlands, their populations are greatly threatened by losses of that type of habitat. Wetlands are disappearing or being otherwise degraded in most parts of the world. This is occurring as a result of infilling of wetlands to develop land for urbanization, draining for agriculture, and pollution by pesticides and fertilizers.