Aspectos da ontogenia do Jacu-guaçu (Penelope obscura bronzina Hellmayr, 1914), segundo levantamento em cativeiro

Abstract

This study presents data on the biology of the Dusky-legged Guan (Penelope obscura bronzina Heflmayr, 1914) in captivity, with special emphasis on its ontogeny. Nutrition seemed to have a direct influence on the size of the eggs. ln 3 years 279 eggs were recorded, 36% of which were fertile. From these, 77% have hatched, but 19% of the chickens died. 63 chickens were studied and 33 of these up to 6 months. The measures of the culmen, tarsus and wing and the weight of the young were taken biweekly. The wing had the greatest relative growth in the first 15 days, while the culmen, tarsus and the weight had grew most during the first 4 weeks. Except for weight, the coefficients of biweekly growth determined that the development of the young tended to stabilize after 120 days. However, the graphics of the culmen and weight did not stabilize until 6 months. The young passed through a juvenal phase with soot-coloured feathers on the mantle and on the lesser wing-coverts, while in the adult these parts were black with a green gloss and the lateral edges of the feathers were white. There was considerable variation in the pattern colouration of the birth plumage of the chickens and no characteristic was found to determine the sex, even in relation to the bare parts . By 90 days the young Dusky-legged Guan was very much like the adult, though some parts of the plumage had moulted more than one time and others only once. Sexual maturity was reached when the bird completed 1 year. The successful reproduction of a pair on one season didn't mean that the sarne would happen in the next.