Biologia reprodutiva de Sturnira lilium (Chiroptera, Phyllostomidae) na Floresta Atlântica do estado do Rio de Janeiro, sudeste do Brasil

Abstract

Bats can be monoestrous or polyestrous, and seasonal or non-seasonal in their reproductive patterns. The strategy adopted by each species or population depends on the regional climate. For the bats of South America there is still no comparative study of the possible reproductive strategies, with few species that have had their biology analyzed in detail. The objective this study was to analyze reproductive data of Sturnira lilium from long-term sampling carried out in several sites in Rio de Janeiro states, southeastern Brazil. We carried out sampling in 64 sites (with altitudes ranging from 0 to 1.300 m a.s.l.) from May 1989 to December 2011. In total, we obtained 2602 captures of S. lilium: 1.242 adult females, 1.225 adult males, and 136 subadults. The sex ratio was 0,99 males: 1 female, varying a little among months. The proportion of males with scrotal testes was higher in months when the percentage of potentially receptive females was higher. Long-term studies and with many local variations inhibit the variation in end sexual proportion. We recorded pregnant every month, except July and lactating females in all months. This pattern is an indication rating for a reproductive event non-seasonal. The proportion of males with testes evident was higher in the months when there was a higher percentage of potentially receptive females. Species of tropical bats have shown males with spermatogenesis expanded when females are receptive to estrus postpartum. The production of male gametes must be synchronized with the cyclicity of the females. The duration of the reproductive event ranged annually and is independent of accumulated precipitation. Only with long samples and with different conditions we will recognize the strategies adopted by each species in each locality and, therefore, the samples annually are unrepresentative. This variation demonstrates adaptability to annual and multi-annual cycles of precipitation, as observed in other species of bats and show that local variations can also be expected as crucial factor for the reproductive period. In the present study, the highest proportions of pregnant and lactating females were observed in the months of highest precipitation favoring the lactation period and creates of pups at the time of greatest food availability. However, there was no linear relationship of the percentage of lactating females with the same climatic variations. The rainiest months are also the hottest, it is difficult to distinguish the role of each variable in determining the reproductive seasonality of S. lilium. We conclude that Sturnira lilium presents non-seasonal polyestrous reproduction with postpartum estrus and early reproductive event is influenced by the increase in rainfall for this species in this longitude.