Herpetology Notes, volume 13: 1069-1071 (2020) (published online on 22 December 2020)

Diurnal resting sites and colouration in two species of Bornean rhacophorids, otilophus and pardalis

Kaede Kimura1,*, Akihiro Noda1, Yosuke Kojima2, Kanto Nishikawa3,4, and Mohamad Yazid Hossman5

Anurans display a striking diversity of colouration 1893) and Rhacophorus pardalis Günther, 1858, based which is often closely tied with avoiding predators, on our radiotelemetric research. the most widespread function of which is camouflage is a large tree , with (Rojas, 2017). Cryptic body colour prevents detection yellowish brown dorsal colouration and numerous black or recognition of anurans by their predators (Cooper et stripes. It occurs in lowland primary and secondary al., 2008). To elucidate the function or effectiveness of forests as well as disturbed environments on Borneo presumably cryptic colouration, we must investigate (Malkmus et al., 2002). Predation by a bird on this whether body colouration serves as camouflage during species has been observed during the day (Shiozaki and the day rather than night because visually-oriented Nishikawa, 2017). Rhacophorus pardalis is a small to predators, such as birds, usually forage diurnally. medium-sized tree frog, whose dorsal colour is tan to Diurnal resting sites can include various shelter reddish brown with dark markings and irregular white types, such as leaf litter, cracks on the ground, tree spots. It can be found in primary and secondary forests holes, and leaf surfaces (Leary and Razafindratsita, at low elevations in Peninsular Malaysia, Borneo, 1998; Lemckert and Slatyer, 2002; Nunes and Costa, Sumatra, and the Philippines (Malkmus et al., 2002). 2011), and benefit from selecting microhabitats Both species reproduce on overhanging vegetation enhancing the performance of their cryptic colouration. above pools of standing water (Malkmus et al., 2002). However, the relationship between resting site selection We radio-tracked two males of Polypedates otilophus and colouration during the day has not been well and one female of Rhacophorus pardalis from 18 to studied. Here, we report several observations of diurnal 23 August 2018 at the Kubah National Park, Sarawak, resting behaviour and colouration displayed from two Malaysia (1°36’46” N, 110°11’49” E). The study was rhacophorid species, Polypedates otilophus (Boulenger, conducted around the “Frog Pond” in the park, which was a permanent pond surrounded by lowland primary forests. Various species of anurans including studied species reproduce in and around this pond. The tracked individuals were collected during the nights on 17-18 August and released back to the captured site within a 1 Division of Biological Science, Graduate School of Science, day, after radio transmitter attachment. The total weight Kyoto University, Oiwake-cho, Sakyo-ku, Kyoto 606-8502, of the transmitter (HOLOHIL Systems Ltd., Canada) Japan. and the attachment (plastic waistband) was 0.6 g, 2 Department of Biology, Faculty of Science, Toho University, Miyama 2-1-1, Funabashi, Chiba 274-8510, Japan. 2.3–3.5% of the frogs’ body mass, which would have 3 Graduate School of Human and Environmental Studies, Kyoto minimal effects on their movements (Madison et al., University, Yoshida Nihonmatsu-cho, Sakyo-ku, Kyoto 606- 2010). Each day after release we attempted to locate 8501, Japan. each individual once during the day and once or twice 4 Graduate School of Global Environmental Studies, Kyoto at night until 23 August (overall four times during the University, Yoshida Hon-machi, Sakyo-ku, Kyoto 606-8501, day and six times at night). The signals were received Japan. using a Yagi antenna and a receiver (IC-R10; Icom 5 Research, Development and Innovation Division (RDID), Sarawak Forest Department, 93250, Kuching, Sarawak, Inc., Japan). Fifteen markers were placed in the study Malaysia. area with tape, and the distance and the angle from * Corresponding author. E-mail: [email protected] the nearest marker to the tracked individuals were 1070 Kaede Kimura et al. measured for mapping location. We sometimes it quantitatively. The body colour appeared yellowish failed to directly observe the tracked frogs because they with clear stripes when the frog was active at night, frequently climb up trees where dense leaves prevent us while tan when resting at the tree segment, and much from locating them by sight. In such cases, we estimated paler when on the dead leaf (Fig. 1). the approximate location by measuring the angle that We observed the Rhacophorus pardalis three times the strongest signals came from and comparing it from of 10 tracking events, in which the frog was found on several sites. We could estimate which tree the frog was leaves at heights from 110 to 215 cm. When we could utilising, but it was impossible to accurately estimate its not directly locate the frog, we estimated the height height. at higher than two meters. The daily travel distances Combining the results of two individuals of P. otilophus, ranged from 25 cm (moving from one leaf to another their location was directly observed seven times and just in the same tree) to 8.3 meters horizontally, and this estimated in the other 13 times. We could not identify individual remained near the Frog Pond (within 10 exact locations because the frogs had climbed more than meters from the pond) throughout the study period. For two meters high and escaped from our sight. Polypedates R. pardalis, we observed the diurnal resting behaviour otilophus used leaves (four times), branches (twice), and only once, on a green leaf about 110 cm above ground trunks (once) at heights from 30 to 230 cm. However, at 15:04 h on 20 August. The background leaf greatly as we only measured height when direct positioning differs in colour from the frog (Fig. 2B). The intraday was possible, this species likely uses much higher parts colouration changes within the individual, if present, are of the forests as well. Daily movements were four to less clear than P. otilophus (Fig. 2). seven meters horizontally, except in a case that one In our short-period survey, we observed tree frogs do individual left the Frog Pond and moved about 30 m not always choose diurnal resting sites matching their in one night. Diurnal resting behaviour was observed own colouration (Fig. 1C, 2B). Although anurans are in only one of the two tracked individuals. The first capable of matching background colours by microhabitat observation was on the tree segment 67 cm above the selection and colouration change (King et al. 1994; ground at 17:38 h (local time, UTC +8) on 21 August. Wente and Phillips, 2005), our observations suggest The dorsal colouration of the P. otilophus was pale that P. otilophus and R. pardalis do not rely solely on brown with grey stripes, matching the colour of the bark the background matching to avoid predators. However, behind the animal (Fig. 1B). On the second observation this does not necessarily mean that these frogs are the tracked individual used a dead leaf 30 cm above easily found by their predators. For example, the frogs the ground at 15:50 h on 23 August, where the whitish might be masquerading as a dead leaf; masquerading dorsal colour was in contrast with the background (Fig. is an antipredator strategy, where an animal resembles 1C). Also, the dorsal colouration might have changed an object that is uninteresting to their predators (Rojas, between the observations, although we did not measure 2017). Factors other than predator avoidance could

Figure 1. The tracked Polypedates otilophus (a) at night conditions two days after the release, and (b) at the first and (c) the second observation of diurnal resting. Photos by K. Kimura and A. Noda. Diurnal resting sites and colouration in two species of Bornean rhacophorids 1071

Figure 2. The tracked Rhacophorus pardalis (a) at night conditions soon after the release and (b) at the daytime resting on a leaf. Photos by K. Kimura and A. Noda.

also affect their diurnal resting sites and colouration. Lemckert, F.L., Slatyer, C. (2002): Short-term movements and Humidity is important for daytime shelter selection habitat use by the threatened Green-thighed Frog Litoria (Cohen and Alford, 1996), and temperature can alter brevipalmata (Anura: ) in mid-coastal New South Wales. Australian Zoologist 32: 56–61. frogs’ body colour (King et al., 1994). Further research Madison, D.M., Titus, V.R., Lamoureux, V.S. (2010): Movement with quantitative measurements of surrounding patterns and radiotelemetry. In: ecology and environments are essential for revealing selection of conservation: a handbook of techniques. Dodd, Jr., C.K., Ed. diurnal resting sites. New York, United States of America, Oxford University Press. 185–202 pp. Acknowledgements. The State Government of Sarawak kindly Malkmus, R., Manthey, U., Vogel, G., Holfmann, P., Kosuch, J. permitted us to conduct our survey and study tour in Kubah NP (2002): and reptiles of Mount Kinabalu (North (Research Permit No. [133]JHS/NCCD/600-7/2/107 and Park Borneo). Ruggell, A.R.G. Gantner. Permit No.WL72/2018), and Kubah NP and RDID provided Nunes, I., Costa, F.R. (2011): “Hide and seek”: diurnal refuge facilities for conducting research. We are grateful to S. S. Yong, and camouflage of two anurans from the Atlantic Forest of R. ak S. Pungga, P. ak Meleng, and T. Itioka for their support Northeastern Brazil. Herpetology Notes 4: 431–433. in obtaining permission to conduct research. We also thank Rojas, B. (2017): Behavioural, ecological, and evolutionary aspects T. Shimada, C. A. Barnett, and the two reviewers for valuable of diversity in frog colour patterns. Biological Reviews 92: suggestions on the manuscript. This study was partly supported 1059–1080. by the Asahi Glass Foundation, JSPS Core-to-Core Program Type Shiozaki, T., Nishikawa, K. (2017): Polypedates otilophus (File- B. Asia-Africa Science Platforms (Coordinator: M. Motokawa), eared Tree Frog). Predation. Herpetological Review 48: 415. and JST/JICA, SATREPS to K. Nishikawa and Y. Kojima. Wente, W.H., Phillips, J.B. (2005): Microhabitat selection by the Pacific Treefrog, Hyla regilla. Animal Behaviour 70: 279–87. References

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