Fidelidade ao sítio por aves seguidoras de formigas-de-correição em florestas primárias e secundárias da Amazônia Central

Abstract

Site-fidelity, measurable as the probability that animals return to or remain in a previously occupied site, has important implications for wildlife science and management. Theory suggests high faithfulness under specific conditions where homogenously-distributed resources are available throughout the lifetime of an individual. These conditions, nonetheless, are frequently not fulfilled. We hypothesized the lack of site-fidelity among Amazon tropical-forest ant-following birds that rely on unpredictable and heterogeneously distributed resources. This study tested the predictions that site-fidelity among ant-following bird is: 1) lower in secondary than in primary forest sites, 2) lower for obligate ant-followers than for facultative ant-followers and, 3) lower for ant-followers than for non-ant-following species of the same family, habitat, and size. We used a Bayesian approach in a multi-state mark-recapture model to estimate survival, recapture and transitions probabilities between primary forest and secondary growth sites. We measured site fidelity in two alternative ways: a) apparent survival probability at a given site; and b) as the probability of remaining at a given site at time t+1, given that the individual was at the same site at time t and survived from t to t+1. Contrary to our expectation ant-followers were more site-faithful to secondary forest than to old growth; nonetheless, low recapture rates in secondary forest suggest that individuals may have to move more to find colonies and satisfy their prey needs in secondary forest than in primary forest. The apparent survival of non ant-followers in secondary growth was lower than the apparent survival of ant-followers in the same environment; yet, we believe that non-ant-following adults with territories established in secondary forest will be as faithful to their site as are non-ant-following adults with territories in old growth. This study suggests that ant-following birds use the 25-30 year secondary growth in our study area with the same or higher site-fidelity that they have to adjacent old growth forest.