Sensory integration during foraging: the importance of fruit hardness, colour, and odour to brown lemurs
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Animal reliance on fruit signals, such as hardness, colour, and odour, during foraging is poorly understood. Here, we present data on fruit foraging behaviour and efficiency (rate of fruit ingestion) of three groups of wild, frugivorous brown lemurs (Eulemur fulvus, N = 29 individuals) in Ankarafantsika National Park, Madagascar. We quantify fruit hardness using a modified force gauge, fruit colour using spectroscopy, and fruit odour using volatile organic compound (VOC) sampling with gas chromatography-mass spectrometry. We relate lemur foraging behaviour to fruit traits by calculating touching, visual inspection, and sniffing indices and relate lemur foraging efficiency to fruit traits by calculating acceptance indices. The use of different sensory modalities by lemurs is marginally predicted in one case by fruit traits—fruits with higher overall smell signals are sniffed less than fruits with lower overall smell signals. When controlling for all fruit traits, fruit size is the only significant predictor of fruit foraging efficiency—lemurs forage more rapidly on smaller fruits relative to larger fruits.
KeywordsBrown lemurs Colour vision Olfaction Volatile Organic Compounds Frugivory Fruit choice Madagascar
We thank MICET and Madagascar National Parks, for permission to conduct this research in Madagascar. We thank Dr. Scott Mabury for the loan of instrumentation. We are grateful to Paul Tsiveraza, Francette, Mamy Razafitsalama and Jean de-la-Dieu for contributions in the field. For helpful commentary, we thank Drs. Mary Silcox, Joyce Parga, Esteban J. Parra, Esteban Fernandez-Juricic, Theo C.M. Bakker and two anonymous reviewers. For funding, we thank Sigma Xi, GM Women in Science (KV), the University of Toronto and Natural Sciences and Engineering Research Council of Canada (NSERC) (KV) and NSERC, and the Canada Research Chair Program aided in the writing stage.
Conflict of interest
The authors declare that they have no conflict of interest.
This study complies with all national and regional laws dealing with ethics and animal welfare in both Madagascar and Canada (University of Toronto (Animal Care Protocol #20009112).
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