Title

Nocturnal Flying Insects and Environment Characteristics as Determinanats of Microchiropteran Abundance in Biak na Bato National Park, Bulacan

Date of Award

2019

Document Type

Thesis

Degree Name

Master of Science in Biology

Department

Biology

First Advisor

Hendrik Freitag, PhD

Abstract

Microchiroptera are insectivorous bats that use echolocation to forage and hunt in the dark. In the Philippines, they are studied for their remarkable species richness and diversity, but then very few studies are focused on their ecology. In the present study, flying insectivorous bats were quantitatively sampled all together with food (insect) and habitat factors including insect abundances, insect body size classes, insect diversity, distance to water, percent canopy cover, presence of vegetation gap and edge, and presence of bamboo clusters in BNBNP. Bat species abundance data and all habitat and food related variables were processed by means of multivariate statistical ordination (CCA) and tested for correlations. The collection resulted in records of eight species of insectivorous bats in BNBNP, with Myotis horsefieldii (Temminck, 1840) being the dominant species. The habitat factors showed stronger correlations compared to food-related factors. Distance from water bodies was strongly correlated (r2 = 0.50) with bat abundances, affecting particularly Rhinilophus arcuatus (Peters, 1871), Rhinolophus macrotis (Blyth, 1844), Hipposideros diadema (Geoffroy, 1813) and Miniopterus australis (Tomes, 1859) assemblages. This suggests that their feeding habitats were relatively far from water bodies. Meanwhile, M. horsefieldii and Hipposideros pygmaeus (Waterhouse, 1843) predominantly occurred near or above water bodies. The presence of vegetation edge and gaps was moderately correlated (r2 =0.40) to M. horsefieldi abundance. Also, it was slightly correlated with flying insects with >1mm2 body size (r2 =0.23). H. pygmaeus showed generalist behavior in terms of habitat preferences since it was observed both in riparian and non-riparian habitat. The presence of forest (r2 =0.23) and Hymenopteran abundance (r2 =0.20) were slightly correlated to R. arcuatus, R. macrotis, M. v autstralis, and H. diadema assemblage. Other insect-related factors showed very weak correlation (r2 =0.18) towards Microchiropteran abundance. These findings might imply that food related factors partly affect Microchiropteran abundance, although it appears that habitat factors play a more crucial role on their occurrence and abundance.

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