Everything about Rail Bird totally explained
The
rails, or
Rallidae, are a large
cosmopolitan family of small to medium-sized
birds. The family exhibits considerable
diversity and the family also includes the
crakes,
coots, and
gallinules. Many
species are associated with
wetlands, although the family is found in every
terrestrial habitat except dry
deserts,
polar regions and
alpine areas above the
snow line.
The most typical family members occupy dense
vegetation in damp environments near
lakes,
swamps, or
rivers.
Reed beds are a particularly favoured habitat. They are
omnivorous, and those that
migrate do so at night: most
nest in dense vegetation. In general, they're shy and secretive birds, and are difficult to observe.
Most species walk and run vigorously on strong legs, and have long toes which are well adapted to soft, uneven surfaces. They tend to have short, rounded wings and although they're generally weak
fliers, they are, nevertheless, capable of covering long distances.
Island species often become
flightless, and many of them are now
extinct following the introduction of terrestrial
predators such as
cats,
rats and
pigs.
Many reedbed species are secretive (apart from loud calls),
crepuscular, and have laterally flattened bodies. In the
Old World, long-billed species tend to be called
rails and short-billed species
crakes.
North American species are normally called rails irrespective of bill length. The smallest of these is the
Swinhoe's Rail, at 13 cm (5 inches) and 25 grams.
The larger species are also sometimes given other names. The black
coots are more adapted to open water than their relatives, and some other large species are called
gallinules and
swamphens. The largest of this group is the
Takahē, at 65 cm (26 inches) and 2.7 kg (6 lbs).
The rails have suffered disproportionally from human changes to the environment and it's estimated that several hundred species of island rail have become extinct because of this. Several island species of rail remain
endangered and
conservation organisations and governments continue to work to prevent their extinction.
Members of the Rallidae are found on every continent except
Antarctica. There are numerous island species. The most common habitats are
marshland or dense forest. Rails are especially fond of dense vegetation.
Morphology
The rails are a fairly homogeneous family of small to medium sized ground living birds. They vary in length from 12 cm to 63 cm and in weight from 20 g to 3000 g. Some species have long necks and in many cases they're laterally compressed, giving rise to the expression
as thin as a rail. The bill is the most variable feature within the family, in some species it's longer than the head (like the
Clapper Rail of the Americas), it may be short and wide (as in the
coots), or massive (as in the
purple gallinules). A few coots and gallinules have a "frontal shield", which is a fleshy rearward extension of the upper bill. The most complex frontal shield is found in the
Horned Coot.
Rails exhibit very little
sexual dimorphism in either
plumage or size.
Flight and flightlessness
The wings of all rails are short and rounded. The
flight of those Rallidae able to fly, while not very powerful, can be sustained for long periods of time and many species undertake annual
migrations. The weakness of their flight, however, means that they're easily blown off course and thus are common
vagrants, a characteristic that has led to them colonising many isolated oceanic islands. Furthermore, these birds often prefer to run rather than fly (especially when in dense habitat). Some are also flightless at some time during their
moult period.
Many island rails are flightless because small island habitats often eliminate the need to fly or move long distances.
Flight makes intense demands, with the
carinatae and flight muscles taking up to a quarter of a bird's weight in Rallidae species. Reducing the flight muscles, along with the corresponding lowering in
metabolic demands, reduces the flightless rail's energy expenditures. For this reason flightless makes it easier to survive and colonize an island where resources are limited. Flightlessness can evolve extremely rapidly in island rails; it took as little as 125,000 years for the
Laysan Rail to lose the power of flight and evolve the reduced, stubby wings only useful to keep balance when running quickly.
Behavior and ecology
In general, members of Rallidae are omnivorous generalists. Many species will eat
invertebrates, as well as fruit or seedlings. A few species are primarily
vegetarian. Loud calls are useful in dense vegetation or at night where it's difficult to see another member of the species. Some calls are
territorial.
Most often, there are five to ten
eggs.
Clutches as small as one or as large as fifteen eggs are known. The
Wake Island Rail was hunted to extinction by the starving Japanese garrison after the island was cut off from supply during
World War II.
At least two species - the
Common Moorhen and the
American Purple Gallinule - have been considered
pests. Some species which came close to extinction, such as the
Lord Howe Woodhen, and the
Takahē, have made modest recoveries due to the efforts of conservation organisations. The
Guam Rail came perilously close to extinction when
Brown tree snakes were introduced to
Guam but some of the last remaining individuals were taken into captivity and are breeding well, although attempts to reintroduce it have met with mixed results.
Systematics and evolution
The family Rallidae has traditionally been grouped with two families of larger birds, the
cranes and
bustards, as well as several smaller families of usually "primitive" mid-sized amphibious birds, to make up the order
Gruiformes. The alternative
Sibley-Ahlquist taxonomy, which has been widely accepted in America, raises the family to ordinal level as the
Ralliformes. Given the uncertainly about gruiform
monophyly, this may or may not be correct; it certainly seems more justified than most of the Sibley-Ahlquist proposals. On the other hand, such a group would probably also include the
Heliornithidae (finfoots and Sungrebe), an exclusively
tropical group that's somewhat
convergent with
grebes, and usually united with the rails in the Ralli.
Extant (living) genera
Additionally, there are many prehistoric rails of extant genera, known only from
fossil or subfossil remains, such as the
Ibiza Rail (
Rallus eivissensis). These have not been listed here; see the genus accounts and the articles on
fossil and
Late Quaternary prehistoric birds for these species.
Recently extinct genera
Genus Nesotrochis - cave-rails (3 species; extinct prehistoric or later)
- Antillean Cave Rail, Nesotrochis debooyi (Puerto Rico and Virgin Islands, West Indies) - may have survived until historic times
- Haitian Cave-Rail, Nesotrochis steganinos (Haiti, West Indies) - prehistoric
- Cuban Cave-Rail, Nesotrochis picapicensis (Cuba, West Indies) - prehistoric
Genus Diaphorapteryx - Hawkins' Rail (extinct 19th century)
Genus Aphanapteryx (2 species; extinct mid-18th century)
Genus Cabalus - Chatham Rail (sometimes included in Gallirallus; extinct c. 1900)
Genus Mundia - Ascension Flightless Crake - formerly included in Atlantisia; (late 17th century)
Genus Aphanocrex - St Helena Swamphen (formerly included in Atlantisia; extinct 16th century)
The undescribed Fernando de Noronha Rail, genus and species undetermined, probably survived to historic times.
Late Quaternary prehistoric extinctions
Genus Capellirallus - Snipe-rail
Genus Vitirallus - Viti Levu Rail
Genus Hovacrex - Hova-gallinule
and see genus accounts
Fossil record
Genus Eocrex (Wasatch Early Eocene of Steamboat Springs, USA)
Genus Palaeorallus (Wasatch Early Eocene of Wyoming, USA)
Genus Parvirallus (Early - Middle Eocene of England)
Genus Aletornis (Bridger Middle Eocene of Uinta County, USA) - includes Protogrus
Genus Fulicaletornis (Bridger Middle Eocene of Henry's Fork, USA)
Genus Latipons (Middle Eocene of Lee-on-Solent, England)
Genus Ibidopsis (Hordwell Late Eocene of Hordwell, UK)
Genus Quercyrallus (Late Eocene -? Late Oligocene of France)
Genus Belgirallus (Early Oligocene of WC Europe)
Genus Rallicrex (Corbula Middle/Late Oligocene of Kolzsvár, Romania)
Rallidae gen. et sp. indet. (Late Oligocene of Billy-Créchy, France)
Genus Palaeoaramides (Late Oligocene/Early Miocene - Late Miocene of France)
Genus Paraortygometra (Late Oligocene/?Early Miocene -? Middle Miocene of France) - includes Microrallus
Genus Pararallus (Late Oligocene? - Late Miocene of C Europe) - possibly belongs in Palaeoaramides
Rallidae gen. et sp. indet. (Bathans Early/Middle Miocene of Otago, New Zealand)
Rallidae gen. et sp. indet. (Bathans Early/Middle Miocene of Otago, New Zealand)
Genus Miofulica (Anversian Black Sand Middle Miocene of Antwerp, Belgium)
Genus Miorallus (Middle Miocene of Sansan, France -? Late Miocene of Rudabánya, Hungary)
Genus Youngornis (Shanwang Middle Miocene of Linqu, China)
Rallidae gen. et sp. indet. (Sajóvölgyi Middle Miocene of Mátraszõlõs, Hungary)
Rallidae gen. et sp. indet. (Middle Miocene of Grive-Saint-Alban, France)
Rallidae gen. et sp. indet. (Late Miocene of Lemoyne Quarry, USA)
Rallidae gen. et sp. indet. UMMP V55013-55014; UMMP V55012/V45750/V45746 (Rexroad Late Pliocene of Saw Rock Canyon, USA)
Rallidae gen. et sp. indet. UMMP V29080 (Rexroad Late Pliocene of Fox Canyon, USA)
Genus Creccoides (Blanco Late Pliocene/Early Pleistocene of Crosby County, USA)
Rallidae gen. et sp. indet. (Bermuda, West Atlantic)
Doubtfully placed here
These taxa may or may not have been rails:
Genus Ludiortyx (Late Eocene) - includes "Tringa" hoffmanni, "Palaeortyx" blanchardi, "P." hoffmanni
Genus Telecrex (Irdin Manha Late Eocene of Chimney Butte, China)
Genus Palaeocrex (Early Oligocene of Trigonias Quarry, USA)
Genus Rupelrallus (Early Oligocene of Germany)
Neornithes incerta sedis (Late Oliogocene of Riversleigh, Australia)
Genus Euryonotus (Pleistocene of Argentina)
The presumed scolopacid wader Limosa gypsorum (Montmartre Late Eocene of France) is sometimes considered a rail and then placed in the genus Montirallus.
Footnotes
Further Information
Get more info on 'Rail Bird'.
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