Dinâmica da ocorrência de papa-formigas (Aves: Thamnophilidae) em uma parcela de floresta primária de terra firme

Abstract

Although tropical bird populations were considered for a long time as more stable than their temperate counterparts, it is known that tropical variation in rainfall throughout the year can bring seasonal variations to food availability and changes in microclimatic conditions of the forest, which can possibly affect birds, making them move in search of resources. We studied static and dynamic occupancy parameters between 14 species of antbirds, to compare their use of space before and after the rainy season. We divided them into three groups, according to their social and foraging habits: solitary (SL), mixed-species flock followers (MF) and army-ant followers (AF). We tested predictions that AF would present more variation in location of occupied sites than both groups, and that MF would show more variation than SL. We surveyed vocalizations of antbirds in 55 points distributed evenly in 928-ha of continuous primary forest, just before and just after the rainy season, employing point counts and autonomous recording during early morning. Data were analyzed, accounting for imperfect detection, using Markov Chain Monte Carlo (MCMC). Comparisons of parameters between groups indicated only that detection probabilities of AF are lower than SL and MF. Lower detection of AF possibly indicates that they are less available to detection since they move more; considering also P. rufifrons’ (AF) noticeable changes in occupied sites, we believe that AF show more variation than SL and MF. Canopy MF seem to be more prone to variation than understory MF, since understory MF, along with SL did not show evidence of changes.