História natural do cardeal-amarelo Gubernatrix cristala (aves: Thraupidae) no Brasil

• Autor(a) principal: Beier, Christian
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da PUC_RS
• Texto Completo: http://tede2.pucrs.br/tede2/handle/tede/6846
• topic: PÁSSAROS - ECOLOGIA; PÁSSAROS - RIO GRANDE DO SUL; ORNITOLOGIA; ZOOLOGIA; CIENCIAS BIOLOGICAS::ZOOLOGIA

The Yellow Cardinal, Gubernatrix cristata, is a threatened passerine that had its populations drastically reduced, mainly by illegal capture and wildlife trade, and habitat loss. Natural history information of the species is few and often innacurate. In order to raise awareness of the Yellow Cardinal and provide subsidies for its conservation, we studied the autecology of the Brazilian population of Yellow Cardinal. Our study was conducted in the municipality of Barra do Quaraí, westernmost State of Rio Grande do Sul, Brazil, during two breeding seasons (October to February, 2013–2015), after a brief pilot-study that started in 2012. We ringed 35 (seven females, 14 males and 14 young) out of 53 individuals found, and by September 2015, the whole Brazilian population of Yellow Cardinal had 38 individuals. We monitored 30 nests, where we observed various aspects of species autecology. We found evidence that leaves may be an important food item in species diet. The adults sex ratio is 1.5:1 and the lifespan is at least 8 years. Pairs are socially monogamous and territorial, with male-biased philopatry and female-biased dispersion. Mean size of breeding territories is 18 ha and mean home range is 27.7 ha. Some pairs and nests (23%) are attended by one or two additional individuals (nest helpers), which contribute on nest and territory defence, and on feeding of nestlings and fledglings. Breeding season starts from first week of October, with a peak of active nests in mid-November and lasts until mid-February. The open-cup nests are built in six days by female, almost all of them in Prosopis affinis, at mean nest height from ground of 2.4 m. Clutch size is three eggs, which female incubates during 12.9 days. The hatching rate is 76% and nestlings fledge after 16 days. Parental care is biparental or cooperative, and the pair have high frequency of visits to the nest than helpers. Nestling survival rate is 67% with mean productivity of 1.6 fledgling per successful nest, and was higher in nests attended by helpers. We recorded second broods after successful attempts, on which helpers were present. Mean interval between nesting attempts was 15.6 days and mean distance was 220.7 m. Shiny Cowbird, Molothrus bonariensis, parasites nests of Yellow Cardinal, with frequency of 67% and intensity of 1.9 egg per parasitized nest. Punctured eggs by female cowbirds led to abandonment of 15% of parasitized nests. From six nests where cowbirds hatched, in two (33%) Yellow Cardinal successfully fledged. Nestlings can be parasitized by botfly larvae (Philornis sp.), with prevalence in 33% of nests where nestlings hatched. Predation was the main cause of nest losses (73%) and we recorded a Leopardus geoffroyi preying on a nest with eggs. The apparent nest success was 27% and the Mayfield nesting success was 18%. The fledgling survival rate during the first month outside the nest was 62%. We recorded a case of inbreeding, between father and daughter. Large home range needs and factors that may adversely affect breeding success (e.g. inbreeding, predation, parasitism) can aggravate the status of the Brazilian population and species. It reinforces the importance of autecology studies and their contribution to the conservation schemes.