Seasonal variation in the diet of the bat Anoura caudifer (Phyllostomidae: Glossophaginae) at the southern limit of its geographic range

摘要

Glossophagine bats feed mainly on flower products, but often eat also insects and fruits. The composition of their diet may change according to climate seasonality. In the present study we analyzed the diet of the bat Anoura caudifer at the southernmost limit of its geographic distribution, the Atlantic Forest of southern Brazil. We identified food items and plant species consumed by A. caudifer and tested the hypothesis that its diet varies seasonally. We collected fecal material monthly from October 2003 to September 2004 in a day roost of A. caudifer. We obtained a total of 1,166 fecal samples: 1,029 (88%) samples contained pollen, 592 (51%) contained insects, and 196 (17%) contained seeds. The hypothesis that diet varies seasonally was corroborated. There was high consumption of nectar and pollen in all seasons, especially in spring (98%), high consumption of insects mainly in summer and autumn (60%), and high consumption of fruits in winter (41%) and summer (24%). Anoura caudifer consumed pollen and nectar of 10 plant species, mainly of Marcgravia polyantha, and fruits of six species, mainly of Piper gaudichaudianum. Anoura caudifer has primarily a pollinivorous/insectivorous diet at the southern limit of its distribution, and, in contrast toother studies, it also eats fruits at some times of the year. Visits to flowers of 10 species, four of which not matching the syndrome of chiropterophily, and consumption of fruits of six species indicate a generalistic behavior of A. caudifer in the study area. This flexibility may have been crucial to the maintenance of A. caudifer populations at the southern limit of its distribution, and also for the persistence of bat-pollinated plants in local ecosystems.