Niche of sympatric insectivorous bats in central Thailand revealed by carbon and nitrogen satable isotopes

Abstract

Foraging is critical for animal survival. Sympatric animals adopt various ways for trophic niche partitioning both in space and time. The study of stable isotope signatures can reveal foraging habitat partitioning and trophic structures used by sympatric insectivorous bat species. This study determined niche partitioning of sympatric insectivorous bats namely Hipposideros larvatus, Chaerephon plicatus, Taphozous melanopogon and T. theobaldi in central Thailand, using carbon and nitrogen stable isotopes from wing tissue and fur. The results showed that wing tissues of each species have different values of isotopic ratio imply interspecific variation in their major diet. Temporal variations in wing tissue infer that these bats altered their diet in different seasons. In wet season, bats foraged more on C4-feeder insects than C3-feeder insects and 815N ranges were lower in all species compared to dry season. Niche width from fur showed that H. larvatus was the greatest followed by T. theobaldi, C. plicatus and T. melanopogon, respectively while wing tissue indicated that H. larvatus was also the greatest following by T. melanopogon, C. plicatus and T. theobaldi, respectively. Niche was slightly overlapped in these four species but more overlapped in dry season, especially those aerial insectivores. Based on wing tissue, the main diet of H. larvatus was coleopteran while T. melanopogon, T. theobaldi and C. plicatus were dipteran. Moreover, this study provided the first report on feeding ecology of T. theobaldi. Their eco- morphological characteristics and echolocation lead to differentiation of habitats and preys of these sympatric bats.