ABSTRACT When foraging on a specific range of fruits or seeds, animals can represent a natural selection force, affecting plant population realized fecundity. Most studies have focused on characteristics of dispersed seeds, but the higher predation of seeds of specific size or shape is also an important force that influences the populations’ realized fecundity and can help to understand patterns of plants genetic variability. In the Brazilian Pantanal, we investigated the predation of Acuri (Attalea phalerata) palm fruits by macaws, whose seeds go intact through tapirs digestive tract and then are deposited on latrines, where they are often consumed by seed predators. We found 251 fruits, containing between 1 and 5 seeds per fruit; 170 were intact and 81 had been partially damaged by macaws, mostly those containing 3 or 4 seeds per fruit and with thin endocarps. We argue that the higher consumption of fruits with these traits reflects a trade-off in the energy spent by macaws to open the fruits and the energy provided by them. Higher predation on 3-4 seeded fruits favors the selection of 1-2 seeded fruits, revealing a selection force opposed to the one exerted by bruchids and small rodents, which favors multi-seeded palm fruits.

ABSTRACT Efficiently obtaining high-quality data on animal populations and communities is paramount for ecological and conservation studies. In many instances these data come from live-trapping, the success of which depends on various factors, such as the interaction between the trap's mechanisms and the morphological or ecological characteristics of the animals, and weather conditions that can affect both trap efficiency and animal behavior. Integrative approaches that address the simultaneous effects of these factors on capture-recapture success are rare. Here we contribute to close this knowledge gap by focusing on a large capture-recapture dataset from three 2-ha grids monitored for approximately two years (totaling 55.000 traps-night) in the Morro Grande Forest Reserve, São Paulo, Brazil. The dataset contains data on 3608 captures of 1273 individuals from 24 species of Atlantic forest small mammals. We evaluated if mortality rates and the capture-recapture success of small mammals varied between two types of trap (Sherman and pitfall), and if the capture success of each type varied with age and sex of individuals, and with weather conditions. Our findings highlight that trap efficiency depends not only on the quantities considered (species, individuals or recaptures), but also on animal characteristics and weather conditions. Large pitfall traps should be used whenever the focus is on biodiversity and community parameters, since they captured more individuals and species. Studies focusing on demographic parameters require the combined use of pitfall and Sherman traps. While pitfall traps captured a larger number of individuals and a higher proportion of juveniles, Sherman traps provided higher recapture rates for most species.

Esse estudo teve o objetivo de descrever flutuações populacionais alternadas para os marsupiais Philander frenatus e Metachirus nudicaudatus na Mata Atlântica, e avaliar as hipóteses de que seriam causadas por capturabilidade diferencial entre espécies e estações, assincronia reprodutiva, diferentes dietas e tolerâncias fisiológicas ou competição interespecífica. Um estudo por captura-marcação-recaptura (1995-2005) mostrou P. frenatus e M. nudicaudatus mais abundantes nos anos secos e úmidos respectivamente. Diferenças nas capturabilidades e reprodução não puderam explicar as flutuações. O padrão pode ser explicado por diferenças de dieta, ligadas a mudanças de disponibilidade de recursos, embora a hipótese de competição não possa ser excluída.

This study aimed to describe reciprocal population shifts for the marsupials Philander frenatus and Metachirus nudicaudatus in the Atlantic Forest, and to evaluate the hypotheses that they were caused by differential trappability between species and seasons, asynchrony of breeding seasons, different diets and physiological tolerances or interspecific competition. A capture-mark-recapture study (1995-2005) showed that P. frenatus and M. nudicaudatus peaked in drier and wetter years respectively. Differences in trappabilities and breeding seasons could not explain fluctuations. The pattern could be explained by differences in diets, coupled to variations in resource availability, although the hypothesis of competition cannot be excluded.