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Individual specialization in the use of space and diet by the frugivorous bat Sturnira lilium

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Patricia Kerches Rogeri
Total Authors: 1
Document type: Doctoral Thesis
Press: Rio Claro. 2018-07-19.
Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
Defense date:
Advisor: Márcio Silva Araujo; Milton Cezar Ribeiro

Most ecology studies treat co-specific individuals as equivalents. However, there has been a growing number of studies that have verified that individuals from the same population can use different subsets of the total resources used by their population, which has been defined as individual specialization. Fruit bats are important seed dispersers and individual specialization in space use and diet can have consequences for this ecological function. In the present study we verified the presence of interindividual variation in the use of space and individual specialization in the diet of the fruit bat Sturnira lilium and investigated possible mechanisms that trigger this variation. To that end, 28 adult individuals were captured in mist net and tagged with radio transmitters monitored by fixed receivers ("dataloggers") distributed in the study area according to landscape characteristics. We studied the diet of these same individuals from fecal samples, focusing on the analysis of the seeds present, and hair samples for stable isotope analysis of carbon and nitrogen. In order to investigate mechanisms that generate such variation, we established the rank preference for each individual, as the ratio between the energy content and handling time of each resource (Optimal Foraging Theory). For this, we performed experiments with 30 individuals to measure handling time. We also measured the energy content of the fruits. We found interindividual variation in space use and this variation was summarized in two movement syndromes: habitat generalist individuals associated with Piper fruits and individual specialized in open areas associated with Solanum. We found that individuals vary mainly in insect consumption, with extremely frugivorous individuals and omnivorous individuals. Stable isotope analysis indicated that the fruit most consumed by all individuals, Solanum, was not the most profitable fruit according to the experiments for half the individuals, for which the most profitable fruit was Piper. This can be pushed by interspecific competition, since there are other species of bats that consume the same resources. These results suggest that the difference in the rank preferences for resources, together with interspecific competition and behavioral characteristics, seem to be the mechanisms that generate the patterns of movement and space use observed in this population of the frugivorous bat S. lilium in a fragmented landscape. (AU)

FAPESP's process: 14/24219-4 - Individual specialization in the use of space and diet by the frugivorous bat Sturnira lilium
Grantee:Patrícia Kerches Rogeri
Support type: Scholarships in Brazil - Doctorate