Densidade populacional e tamanho da área de vida para Formicarius colma (Aves, Formicariidae) em uma parcela de floresta primária na Amazônia Central

Abstract

Spatiotemporal studies of site occupancy have proven useful in wildlife population analysis. Yet, the biological meaning of occupancy often depends on information about the density and movements of organisms, especially when sites lack well-defined boundaries, as in vast unbroken regions of tropical forest. In this study, we provide population density (d), home range size (from parameter σ, which represents the home range standard deviation) and detection probability (ρ) estimates for a population of the Rufous-capped Antthrush (Formicarius colma) in a primary forest plot in Central Amazonia. We captured and color banded 14 individuals of F. colma during June 2011. In the five following months we carried out field surveys to search for the banded birds using playback. We analyzed the data using a SECR model for search-encounter data in a Bayesian framework using MCMC and compared the results with preexisting assessments of F. colma density in the same area. Our posterior estimate for σ was 0.20 Km (95% credible bounds: 0.11 - 0.27). The σ mean was used as the home range radius, leading to a home range area of 12.56 ha, higher than the territory size estimates from previous studies (6.58 and 7.3 ha). Density estimate was 5.7 ind. per 100 ha (95% c.i.: 3.1 8.9), lower than the results previously found (21 and 11 individuals). For the detection probability ρ we got a maximum detection probability at zero distance of 0.40 (95% c.i.: 0.06 - 0.86). The differences between estimates may result from the distinct analytical and data-collection methods used. Differently from the previous works, we used locations only from marked birds, during a longer sampling period, while accounting for imperfect detection.