Designed by Paul Smith 2006. This website is copyrighted by law.
Material contained herewith may not be used without the prior written permission of FAUNA Paraguay.
Photographs on this web-site were taken by Paul Smith, Hemme Batjes, Regis Nossent,
Alberto Esquivel, Arne Lesterhuis, José Luis Cartes, Rebecca Zarza and Hugo del Castillo and are used with their permission.
RALLIDAE - RAILS, CRAKES, GALLINULES AND COOTS
Twenty-three Paraguayan species in this extensive and globally-distributed family. Despite obvious differences in the extremes of the family, attempts to classify this family into subfamilies or tribes have constantly frustrated taxonomists as a great many of intermediate forms both internally and externally represent a clinal variation and the boundaries between supposed subfamilies have never been clarified. Though most modern species are associated with waterside habitats, the ancestral forms likely inhabited woodland and forest. The earliest known rallid fossils date back 50 million years, while DNA evidence suggests that the family may have diverged as much as 85 million years ago. In general rails are small to medium-sized with laterally-compressed bodies, long legs and toes, raised hallux and short-rounded wings. They are often extremely secretive in behaviour but possess loud and distinctive vocalisations. All species can swim, though only the coots and gallinules do so often and are somewhat duck-like in their behaviour. In coots the pelvis is elongated and narrow, a modification for diving, and the toes are lobed to aid swimming. The coots and the gallinules possess frontal shields, which are often colourful. The term "rail" is most often used for larger, longer-billed species, whilst "crakes" are usually smaller, shorter-billed and shorter-legged birds, however neither term has any taxonomic significance. Many species are long-necked, with 14 or 15 cervical vertebrae present. Members of this family have 10 primaries, with a vestigial 11th present in some of the larger species. The plumage is loose. The wings are diastaxic, they lack a 5th secondary. Flight is weak and over short distances usually low with legs dangling. Despite this some species are capable of long migrations. The tail is short and soft, typically with 12 retrices, but less in species with extremely short tails. Contrastingly coloured under-tail coverts present in some species probably have a signalling function. With the exception of Porphyrio the nostrils are located in a depression in the bill and rails apparently possess an excellent sense of smell. Flight feathers are moulted simultaneously. Males are larger than females.
REFERENCES
Campbell B & Lack E 1985 - A Dictionary of Birds - T & AD Poyser.
Ripley SD 1984 - Rails of the World: A Monograph of the Family Rallidae Portfolio Edition - Smithsonian Institution Press.
Taylor B & Van Perlo B 1998 - Rails: A Guide to the Rails, Crakes, Gallinules and Coots of the World - Helm.
