Desenvolvimento pós-embrionário de Nothocrax urumutum (Spix, 1825) em cativeiro (Aves, Cracidae)

Abstract

Described in the first quarter of the 19th century, Nothocrax urumutum remains one of the least known Cracidae, being characterized by unique morphological aspects such as its bare parts and plumage. Between April 1993 and December 1998, it was possible to study the postembryonic development of 28 nestlings of the species raised in the "Cristório Científico Rodeo Drive" at Ilha de Guaratiba, Rio de Janeiro, and 18 of which were monitored for a period of 67 months. The nestlings of Nothocrax urumutum present neossoptile speckled by black, white, brown etc., composing a very complex pattern very similar to the nestlings of Crax and Mitu representatives. ln this sense, the so-called "young" mentioned earlier by different authors consist of specimens less than 130 days old, the plumage of which still keep some neossoptile, while the "immature"or "sub- adult", so often described as "smaller copies of their parents", are not else than 131 to 411 days old individuais that have feathers of second and/or third generation able to be distinguished from those of the fourth generation feathers, which are identical to those of adults regarding colour and shape. As it is happens with other Cracidae, the wing and tail moult of Nothocrax urumutum would proceed from the first to the tenth primaries, from the fifth to the first and twelfth secondaries and from the third to the first and sixth rectrices. The youngs of the species reach 92. 09% of adult weight at about two years old, and 97.31% of adult total lenght with 175 days of life. The culmen, tarsus, wing and tail reach values higher to 90% of the recorded average for adults between the 188º and 209º day of life. On the average, Nothocrax urumutum females reach sexual maturity in two and a half years , while one year old males already present the trachea very similar to adults in terms of size and shape. ln general, the nestlings of Nothocrax urumutum are almost so independent from the parents as the downy youngs of certain Phasianidae, even though the fact that Cracidae are bom with already developed remíges and and upper wing coverts parallels only the Megapodidae. Because of such characteristic, the Megapodidae and Cracidae have often been considered related and very primitive groups, since the conspicuous precouciousness of their youngs corresponds to a plesiomorphy in terms of postembryonic development within the Archosauria.