ABUNDANCE, ROOST CHARACTERISTICS, ACOUSTICS AND DIET COMPOSITION OF SELECTED BAT SPECIES IN SOUTH WAYANAD FOREST DIVISION

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Date
2017
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD
Abstract
Bat species abundance, roost characteristics and selected Rhinolophid bat species call parameters (R. rouxii, R. beddomei and R. pusillus) and diet composition were studied (one fruit bat Cynopterus brachyotis, two species of insectivorous bats Rhinolophus beddomei and R. rouxii) from May 2017 to August 2017 in the South Wayanad Forest Division (SWFD). Bat species abundance was estimated using roost count method. The roost site parameters such as temperature, altitude, canopy cover, humidity and proximity to water body, human settlement and nearest road were noted. Bat call parameters were recorded in the roost site using ultrasound bat detector and analysed using Batsound Software. Bat call was classified using discriminate function analysis. Diet composition of a fruit bat and insectivorous bat species were analysed and micrograph were used to identify prey species. Prey species diversity and similarity in diet composition was calculated. A total of 11 bat species, belonging to five families such as Pteropodidae, Rhinolophidae, Megadermatidae, Emballonuridae and Vespertilionidae were recorded. Among different families Rhinolophidae and Pteropodidae had maximum number of species and abundance. The abundance of bat species was significantly more in Chedeleth Range. The number of bat species recorded and abundance was higher in non forest area than forest area. Present study reported the highest number of P. giganteus in Panamaram river. Among different variables measured in roost site compared between forest and non forest, distance to human settlement and distance to road was significantly higher in forest area. Bat species such as Megaderma spasma, R. beddomei, R. lepidus. R. rouxii recorded from abandoned buildings, rock caves, tunnel and unused wells. P. giganteus roosted only on trees and there were substantial variation in roost tree selection. Among roost site characteristics, roost temperature and altitude varied across species. 59 Three species of Rhinolophidae call parameters such as duration, interval, start and end frequency, FMAX and bandwidth were analysed and found that all parameters varied significantly. Call parameters of R. pusillus is reported for first time. Call parameters have reported to vary in different localities, method of call recording and thus it is essential to study call parameters from Wayanad region. In the present study calls were measured at the roost site when the bats were flying without any constraints. The call parameters of three Rhinolophid species were classified with 100% certainty using discriminate function analysis. A total of 120 droppings of frugivourous bat C. brachyotis were analyzed (both frequency and volume were estimated) and 12 different species of fruits were identified. Plant species belongs to 10 genera and eight families were identified as food plants. Ficus sp. had the highest frequency (46.5%) followed by Psidium guajava (26.7%), Ficus callosa (18.9%) and other species. Diet composition based on volume was different with Gnetum sp. had the highest volume (50.9%) followed by Cinnamomum sp. (12.2%), Ficus sp. (7.5%) and other species. There was significant difference between the volume of fruit and frequency. Diet composition of two Rhinolophid bat species (R. beddomei and R. rouxii) were compared. The major insect prey was similar for both species with Coleoptera, Lepidoptera and Diptera were constituted 80% and 88% in R. beddomei and R. rouxii respectively. Prey species diversity was higher for R. beddomei than R. rouxii. Diet niche overlap based on prey species was 98% similar. Though both species feed on same niche, same insect prey item, morphological differences of bat species, foraging methods and insect prey abundance could enable both species to co-exist in the similar environment
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