Tambopata Macaw Project

Studying avian growth can provide insight in to developmental tradeoffs, offspring size, reproductive output and potential conservation actions. We measured body mass, culmen, wing, and tarsus growth of 45 wild Scarlet Macaw (Ara macao) chicks in the Tambopata region in lowland Peru. Of these, 15 were first chicks, 15 were second chicks in two chick broods, and 15 were only chicks in one chick broods. Chicks fledged in 86 ± 4 days. In general, the growth rates and curves were similar to those found for other members of the order. Chicks in one chick broods gained body mass significantly faster than chicks in two chick broods. However, the peak recorded body masses, asymptotic body masses, and fledging ages did not differ among the chicks in one and two chick broods, suggesting that by the time the chicks fledged, the different growth rates no longer had a significant influence on the birds. Future studies should look at the consequences of manipulating brood sizes of large psittacines as a management technique to determine if fostering additional chicks significantly depresses the growth and post fledging survival of brood mates.