Abstract
In studies on frugivory and seed dispersal, it is frequently assumed that individual frugivores of the same population behave as equivalents. However, there is growing evidence from dietary studies pointing out that, in many natural populations, individuals use different subsets of the total resource pool. As heterogeneity in foraging behavior and food selection may affect the outcome of the seed dispersal process, we tested whether yellow-shouldered bats Sturnira lilium (E. Geoffroy St.-Hilaire, 1810), the key neotropical seed dispersers, show interindividual variations in fruit preferences. Thirty individuals were submitted to cafeteria trials in a flight tent, when they were offered fruits of Solanum variabile Mart. (Solanaceae) Cecropia pachystachya Trec. (Urticaceae), and Piper aduncum L. (Piperaceae), which belong to the favorite genera consumed by S. lilium. Although S. variabile had the highest consumption rates on average, there were variations among individuals in the fruits consumed in the second and third places. These findings, together with interindividual differences in foraging areas observed in the same population, may be interpreted as preliminary evidence of individual specialization. As a possible consequence, frugivorous bats of the same population, despite being all legitimate dispersers, may differ in their efficiency.
We thank many colleagues who helped us in this study. Ariovaldo Cruz-Neto, Elisabeth Kalko, and Susan Barnard helped us with invaluable information about maintaining bats in captivity, building flight tents, and setting up behavioral experiments. Vinicius Kavagutti, Lucas Sacilotto, Débora Motta, Patrícia Rogeri, Pavel Dodonov, and Tiago Andrade assisted us in the field and the experiments. Márcio Araújo helped us with the literature and discussions about individual specialization. Marcelo R. Nogueira helped us in bat identification. Plants were identified by Maria I. S. Lima. Carsten Dormann, Nico Blüthgen, and Vladimir Batagelj advised us on the use of their network software. Kirstin Übernickel gave us suggestions for the statistical analysis. The Federal University of São Carlos and EMBRAPA Pecuária Sudeste provided us with fieldwork infrastructure. The Brazilian Research Council (CNPq, 123569/2010-9), the São Paulo Research Foundation (Fapesp, 2006/00265-0), and the Alexander von Humboldt Foundation (AvH, 1134644) funded our study. This study is dedicated to the memory of our great mentor and friend Elisabeth Kalko.
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