Population dynamics of the black-cheeked gnateater (Conopophaga melanops, Conopophagidae) in southern Brazil

Abstract

Abstract:Population structure and dynamics of the black-cheeked gnateater (Conopophaga melanops) were studied at Salto Morato Nature Reserve, in Paraná, southern Brazil, from October 2006 to September 2007. Territory size and population density, breeding season (timing and length), reproductive success and annual survival rates were estimated from sightings of 18 marked adult birds and the success of 18 nesting attempts. The black-cheeked gnateater is socially monogamous and territorial, with a breeding-season length of approximately 3 mo beginning in early October. Predation caused most nest failures, nest survival was 0.96 d−1and apparent annual nesting success was 22%, resulting in annual productivity of 0.36 individuals per adult. Apparent adult annual survival was ~0.44 y−1. Seventy-five per cent of fledglings survived at least 2 mo after fledging. Two methods of estimating population growth rate suggest very different rates: r = −0.04 (~ stable), or λ varies between 0.475–0.616 (declining). Yet, low apparent adult survival suggests that territories are not permanent, perhaps abandoned after nest failure. We find that by estimating population growth, even in short-term studies, testable hypotheses can be generated that will allow better understanding of population dynamics.