How do Sri Lankan shrub frogs Philautus popularis spend their night time: Field observations from Bolgoda wetland complex

Abstract

Sri Lanka is an amphibian hot spot providing home for 109 species. Nevertheless, studies on ecology and biology of amphibians of Sri Lanka are scarce and behaviour of frogs has drawn even less attention. Philautus popularis (Ranidae, Rhacophorinae; Manamendra-Arachchi & Pethiyagoda, 2005) is an endemic shrub frog which occurs in the low country wet zone. This study attempts to report behaiourlspectrum of P. popularis in an undisturbed wetland in an urban area. Study site comprised of two locations in Bolgoda south lake wetland complex (790 52’ – 790 59’ north longitude and 060 42’ – 06051’ east latitude).

This study was carried out for one months starting from mid June 2009 from 1800 hrs onwards. On each study date, a random path was chosen to walk till a frog was found. The observations were made according to focal animal sampling method, by the naked eye. When an animal was found the total behavioural pattern was studied carefully from a point 1 m away from the frog. Times spent on differentbehavioural activities were noted. A total of 64617 seconds (nearly 18 hours) were spent on differentbehavioural activities.

Twenty nine individuals (26 males and 3 females) were studied and seven behavioural events were encountered: acoustic, locomotion, resting (No movements), foraging, agonistic, cleaning and sexual behaviour. Time taken for each behaviour was compiled taking both sexes into consideration. The mostabundant behaviour event was resting without any movement (45% of the total time) but sometimesthey showed feeding in between. When activities are considered, they were found spending more timefor calling (27.1%, males only) and sexual behavior including amplexus (25%). Interestingly, agonisticbehaviour was shown by males and time taken was 2.1% of total. Walking, cleaning, jumping and climbing took a negligible proportion of the total time and were less than 0.2 percent. Calling was observed from 1800-2300 and they were silent from 0130-0530 and then started acoustic signals again.Perch height of males varied from 40-160 cm from the ground and the highest point was reached aroundmidnight. Females were always near the ground (5-15cm). Males are territorial and it is likely that theirhome range is within a 5m radius.

This shrub frog used minimum time to climbing locomotion pattern and then jumping. The most abundant locomotion pattern was walking, spent 59.6% from the total time for locomotion to the walking. 3 Different perched postures were recorded and climbing position was recorded. Perched height and time has significant relationship respect to both study sites. There is no any preferred plant species for Philautus popularis. They spent 1380 seconds on agonistic behaviour, 2% of the total behavioural observation time. They spent time of 16,200 seconds in amplexing. They hide under leaf litter duringday time.