RALLIDAE

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. Reedbeds are a particularly favoured habitat. They are omnivorous, and those that migrate do so at night: most nest in dense vegetation. In general, they are 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 are 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 Takahe, at 65 cm (26 inches) and 2.7 kg (6 lbs).
The rails have suffered disproportionally from human changes to the environment and it is 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.

Contents

Rallidae biology

Distribution and range

Morphology

Behavior and ecology

Rallidae and humans

Threats and conservation

Systematics, evolution and genera

Extant (living) genera

Recently extinct genera

Late Quaternary prehistoric extinctions

Fossil record

Doubtfully placed here

References

Rallidae biology

Distribution and range

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.^[1]

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 are 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 is 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 gallinules).^[2] 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.^[3]
Rails exhibit very little sexual dimorphism in either plumage or size.
'Flight and flightlessness'

The wings of all volant species (i.e., those able to fly) are short and rounded; the flight of this family, while weak, can be sustained for long periods of time and many species undertake annual migrations. The weakness of their flight, however, means that they are 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.^[4]
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 carina and flight muscles taking up 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.^[5] For this reason flightless makes it easier to survive and colonize an island where resources are limited.^[6] 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.^[7]

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.
The calls of Rallidae species vary and are often very loud. Some are whistle-like or squeak-like, while others are "unbirdlike".^[8] Loud calls are useful in dense vegetation or at night where it is difficult to see another member of the species. Some calls are territorial.^[2]
'Breeding'

The breeding behavior of many Rallidae species are poorly understood or unknown. Most are thought to be monogamous, although polygyny and polyandry have been reported. Firefly Encyclopedia of Birds, Joseph A. Horsfall & Robert Robinson, , , Firefly Books, 2003,
Most often, there are five to ten eggs. Clutches as small as one or as large as fifteen eggs are known.
Upon hatching, which is not always at nearly the same time for an entire clutch, the offspring become mobile after a few days. The offspring will often remain dependent on their parents until fledging, which happens at around one month of age.

Rallidae and humans

The Guam Rail is an example of an island species that has been badly affected by introduced species.

Some of the larger, more abundant rails are hunted and their eggs collected for food.^[10] 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.^[11]
At least two species, the Common Moorhen and the Purple Gallinule, have been considered pests.

Threats and conservation

Due to their tendencies towards flightlessness, many island species have been unable to cope with introduced species. The most dramatic human caused extinctions occurred in the Pacific Ocean as people colonised the islands of Melanesia, Polynesia and Micronesia, during which an estimated 750-1800 species of bird went extinct, half of which were rails.^[12] Some species which came close to extinction, such as the Lord Howe Woodhen, and the Takahe, 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, evolution and genera

Red-legged Crake, ''Rallina fasciata''

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 is somewhat convergent with grebes, and usually united with the rails in the Ralli.

Extant (living) genera

Water Rail, ''Rallus aquaticus''

★ ''Himanthornis'' - Nkulengu Rail

★ ''Sarothrura'' - flufftails (9 species)

★ ''Canirallus'' (2 species)

★ ''Coturnicops'' (3 species)

★ ''Micropygia'' - Ocellated Crake

★ ''Rallina'' - forest-rails (8 species)

★ ''Anurolimnas'' (3 species)

★ ''Atlantisia'' - Inaccessible Island Rail

★ ''Laterallus'' (10 species)

★ ''Nesoclopeus'' (1 living species, 1 recently extinct)

★ ''Gallirallus'' - Austropacific rails (11-12 living species, 3-5 recently extinct)

Immature Spotted Crake (''Porzana porzana'')

★ ''Rallus'' - typical rails (some 9 living species)

★ ''Lewinia'' (3 species; sometimes included in ''Rallus'')

★ ''Dryolimnas'' (1 living species, 1 recently extinct)

★ ''Crecopsis'' - African Crake (sometimes included in ''Crex'')

★ ''Crex'' - Corn Crake

★ ''Rougetius'' - Rouget's Rail

★ ''Aramidopsis'' - Snoring Rail

★ ''Aramides'' - wood-rails (8-9 living species, possibly 1 recently extinct)

★ ''Amaurolimnas'' - Uniform Crake

★ ''Gymnocrex'' (3 species)

★ ''Amaurornis'' - bush-hens (9 species)

★ ''Porzana'' - typical crakes (13 living species, 4-5 recently extinct)

★ ''Aenigmatolimnas'' - Striped Crake

★ ''Cyanolimnas'' - Zapata Rail

★ ''Neocrex'' (2 species)

★ ''Pardirallus'' (3 species)

★ ''Eulabeornis'' - Chestnut Rail

★ ''Habroptila'' - Invisible Rail

★ ''Megacrex'' - New Guinea Flightless Rail

★ ''Gallicrex'' - Watercock

★ ''Porphyrio'' - swamphens and purple gallinules (6 living species, 2-5 recently extinct; includes ''Notornis'' and ''Porphyrula'')

★ ''Gallinula'' - typical gallinules (7-9 living species, 1-3 recently extinct; includes ''Edithornis'' and ''Pareudiastes'')

★ ''Fulica'' - coots (c.10 living species, 1 recently extinct)
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 Island Rail) - formerly included in ''Atlantisia''; extinct (late 17th century)

★
★ Ascension Island Rail, ''Mundia elpenor''

★ Genus ''Aphanocrex'' - St Helena Swamphen (formerly included in ''Atlantisia''; extinct 16th century)

Late Quaternary prehistoric extinctions

★ Genus ''Capellirallus'' - Snipe-rail

★ Genus ''Vitirallus'' - Viti Levu Rail

★ Genus ''Hovacrex'' - Hova-gallinule

Fossil record

★ Genus ''Eocrex'' (Wasatch Early Eocene of Steamboat Springs, USA)

★ Genus ''Palaeorallus'' (Wasatch Early Eocene of Wyoming, USA)

★ Genus ''Aletornis'' (Bridger Middle Eocene of Uinta County, USA)

★ Genus ''Fulicaletornis'' (Bridger Middle Eocene of Henry's Fork, USA)

★ 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: Hugueney ''et al.'' 2003)

★ Genus ''Palaeoaramides'' (Late Oligocene/Early Miocene - Late Miocene of France)

★ Genus ''Paraortygometra'' (Late Oligocene/?Early Miocene of France)

★ Genus ''Pararallus'' (Late Oligocene? - Late Miocene of C Europe)

★ Genus ''Miofulica'' (Anversian Black Sand Middle Miocene of Antwerp, Belgium)

★ Genus ''Miorallus'' (Middle Miocene of Sansan, France -? Late Miocene of Rudabánya, Hungary)

★ Rallidae gen. et sp. indet. (Sajóvölgyi Middle Miocene of Mátraszõlõs, Hungary: Gál ''et al.'' 1998-99)

★ Rallidae gen. et sp. indet. (Late Miocene of Lemoyne Quarry, USA)

★ Rallidae gen. et sp. indet. UMMP V55013/-14; 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''

★ Genus ''Microrallus''

★ Genus ''Parvirallus''

★ Genus ''Youngornis''

★ Rallidae gen. et sp. indet. (Bermuda, West Atlantic)

Doubtfully placed here

These taxa may or may not have been rails:

★ Genus ''Ludiortyx'' (Montmartre Late Eocene of Montmartre, France)

★ Genus ''Telecrex'' (Irdin Manha Late Eocene of Shara Murun, Mongolia)

★ Genus ''Palaeocrex'' (Early Oligocene of Trigonias Quarry, USA)

★ Genus ''Rupelrallus'' (Early Oligocene of Germany)

★ 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'' (Olson 1985).

References

1. Firefly Encyclopedia of Birds, Joseph A. Horsfall & Robert Robinson, , , Firefly Books, 2003,
2. Firefly Encyclopedia of Birds, Joseph A. Horsfall & Robert Robinson, , , Firefly Books, 2003,
3. Firefly Encyclopedia of Birds, Joseph A. Horsfall & Robert Robinson, , , Firefly Books, 2003,
4. Firefly Encyclopedia of Birds, Joseph A. Horsfall & Robert Robinson, , , Firefly Books, 2003,
5. McNab, B. K. & Ellis, H. I. (2006) "Flightless rails endemic to islands have lower energy expenditures and clutch sizes than flighted rails on islands and continents" ''Comparative Biochemistry and Physiology a-Molecular & Integrative Physiology'' '145'(3): 295-311
6. McNab, B. K. (1994) "Energy conservation and the evolution of flightlessness in birds" ''American Naturalist'' '144'(4): 628-642
7. Slikas, B., Olson, S. L. & Fleischer, R. C. (2002) "Rapid, independent evolution of flightlessness in four species of Pacific Island rails (Rallidae): an analysis based on mitochondrial sequence data" ''Journal of Avian Biology'' '33'(1): 5-14
8. Firefly Encyclopedia of Birds, Joseph A. Horsfall & Robert Robinson, , , Firefly Books, 2003,
9. Firefly Encyclopedia of Birds, Joseph A. Horsfall & Robert Robinson, , , Firefly Books, 2003,
10. Firefly Encyclopedia of Birds, , , , Firefly Books, 2003,
11. Wake Island Rail Gallirallus wakensis
12. Steadman D, (2006). ''Extinction and Biogeography in Tropical Pacific Birds'', University of Chicago Press. ISBN 978-0-226-77142-7


★ 'Gál', Erika; Hír, János; Kessler, Eugén & Kókay, József (1998-99): Középsõ-miocén õsmaradványok, a Mátraszõlõs, Rákóczi-kápolna alatti útbevágásból. I. A Mátraszõlõs 1. lelõhely [Middle Miocene fossils from the sections at the Rákóczi chapel at Mátraszőlős. Locality Mátraszõlõs I.]. ''Folia Historico Naturalia Musei Matraensis'' '23': 33-78. [Hungarian with English abstract] PDF fulltext

★ 'Hugueney', Marguerite; Berthet, Didier; Bodergat, Anne-Marie; Escuillié, François; Mourer-Chauviré, Cécile & Wattinne, Aurélia (2003): La limite Oligocène-Miocène en Limagne-changements fauniques chez les mammifères, oiseaux et ostracodes des différents niveaux de Billy-Créchy (Allier, France). ''Geobios'' '36': 719-731 [Article in French with English abstract] (HTML abstract)

★ 'Olson', Storrs L. (1985): Section X.D.2.b. Scolopacidae. ''In:'' Farner, D.S.; King, J.R. & Parkes, Kenneth C. (eds.): ''Avian Biology'' '8': 174-175. Academic Press, New York.