Biologia reproductiva y comportamientos de cuidado parental de dos especies de atajacaminos de córdoba, Argentina

Abstract

Nightjars are insectivorous birds whose mimetic coloration and night activity make them difficult to study. The aim of this study has been to describe aspects of the little-known breeding biology of Little Nightjar (Setopagis parvulus parvulus) and Band-winged Nightjar (Systellura longirostris patagonicus), two sympatric species in the Chaco Serrano formation of the province of Córdoba, Argentina. We observed great similarity in the nest and nesting site of the studied species, as well as in reproductive traits and parental care behaviors. Clutch size of both species was two eggs, and incubation (monitored with temperature sensors and direct observations) was provided mostly by females, whereas males shared the duties a few hours during the day. The incubation period lasted approximately 17 days, and percentage of nest attentiveness was high in both species (Little Nightjar incubated 92.81 ± 2.33% and Band-winged Nightjar incubated 92.39 ± 4.73% per day). No translocation of eggs was documented in any nest, but we observed movements of chicks away from the nest, at distances that increased progressively as the young aged. In both species, growth curves of chicks indicated a size difference between the chicks of the same nest, possibly associated to asynchronous hatching. This study contributes to the knowledge of life history strategies and reproductive behavior of Neotropical nightjars, which so far is limited and deserves future attention.