Impact of Shiny Cowbird and botfly parasitism on the reproductive success of the globally endangered Yellow Cardinal, Gubernatrix cristata

DOMINGUEZ, M.; REBOREDA, J.C.; MAHLER, B.

BIRD CONSERVATION INTERNATIONAL

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2014

0959-2709

The Yellow Cardinal, Gubernatrix cristata, is a globally endangered passerine endemic of southern South America. Although the conservation status of this species is alarming, there is no information about factors that affect its reproductive success. We studied the breeding biology of a Yellow Cardinal population at Corrientes province in NE Argentina, report reproductive parameters, such as timing of breeding, clutch size, hatching success and chick survival and analysed factors that influence nest survival. The breeding season lasted from October to December with most nesting attempts occurring during the second half of November. Renesting after nest failure occurred in approximately 35% of the pairs but we did not observe renesting after successful attempts. Modal clutch size was 3 eggs and successful nests fledged on average 1.6 chicks. We observed brood parasitism by Shiny Cowbirds Molothrus bonariensis in 33% of the nests. The main cost of brood parasitism was the puncture of cardinal eggs by cowbird females, which very often resulted in nest abandonment. Another factor reducing the reproductive success was parasitism by bot flies (Philornis sp.), which occurred in 22% of the nests and reduced chick survival. We determined daily nest survival rate with MARK software and found that during the eggs stage, it decreased with time of breeding and brood parasitism by Shiny Cowbirds. Our results indicate that Shiny Cowbird and bot fly parasitism represent a threat for Yellow Cardinals. Conservation actions to protect the remaining populations of Yellow Cardinals should consider the impact of Shiny Cowbird parasitism.