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.
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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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