Dasia Haliana) in Dry Zone Forests of Sri Lanka
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Herpetological Conservation and Biology 11(2):272–279. Submitted: 24 August 2015; Accepted: 7 May 2016; Published: 31 August 2016. NATURAL HISTORY AND CONSERVATION OF HALY'S TREE SKINK (DASIA HALIANA) IN DRY ZONE FORESTS OF SRI LANKA SURANJAN KARUNARATHNA1,6, THILINA SURASINGHE2, MAJINTHA MADAWALA3, DUSHANTHA KANDAMBI1, THARAKA PRIYADARSHANA4, AND ANSLEM DE SILVA5 1Nature Explorations and Education Team, No: B-1 / G-6, De Soysapura Housing Scheme, Moratuwa 10400, Sri Lanka 2Department of Biological Sciences, Bridgewater State University, Bridgewater, Massachusetts 02325, USA 3South Australian Herpetology Group, South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia 4Department of Natural Resources, Faculty of Applied Sciences, Sabaragamuwa University of Sri Lanka, Belihuloya 70140, Sri Lanka 5Amphibia and Reptile Research Organization of Sri Lanka, 15/1, Dolosbage Road, Gampola, Sri Lanka. 6Corresponding author, e-mail: [email protected] Abstract.—The endemic lizard Dasia haliana of Sri Lanka is considered an arboreal skink. There is little information on the natural history and distribution of this species. To fill-in such knowledge gaps of this endemic skink, we conducted a multi-year survey within the dry and intermediate climatic zones of Sri Lanka and conducted investigations on habitat associations, microhabitat use, foraging, behavior, and basic community structure. Their presence showed close affinities with relatively closed canopy with dappled sunlight, moderate humidity, and high substrate and ambient temperatures. While our study confirmed that D. haliana is primarily arboreal, the skink also occupied non-arboreal (terrestrial and sub-fossorial) habitats to a substantial extend, especially when inactive. We also emphasized the urgent need to promote conservation of D. haliana and other understudied, cryptic herpetofauna of Sri Lanka through a multitude of conservation actions including habitat management inside and outside the protected area network, conservation-driven ecological research, public outreach, and science-based policy revisions. Key Words.—behavior; climate; distribution; ecology; microhabitat; population; threats INTRODUCTION genera such as Eutropis are terrestrial (Das and de Silva 2005). The skink fauna of Sri Lanka is composed of 19 There are 32 species of skinks (Sauria, Scincidae) evolutionary relict taxa belonging to the following found in the Indian Oceanic tropical island of Sri Lanka genera: Chalsidoseps (one species), Lankascincus (10 and of those, 25 are endemic (Karunarathna et al. 2008; species) and Nessia (eight species; Somaweera and Somaweera and Somaweera 2009). Currently, four Somaweera 2009). species are considered Critically Endangered, 13 The members of the genus Dasia (Gray 1839) are Endangered, three Vulnerable, one Near Threatened, and mostly arboreal skinks, and they live on large trees with five Data Deficient (Ministry of Environment 2012). dense canopy cover in dry habitats (Smith 1935; Taylor These national-level conservation assessments are in 1950; Greer 1970; Harikrishnan et al. 2012). Globally, stark contrast to those of the International Union for there are nine species in the genus Dasia with three Conservation of Nature (IUCN) Red List that classifies species restricted to India (Chandramouli and only one Endangered species, one Near Threatened Amarasinghe 2015; Uetz, P., and J. Hallermann. 2015. Species, three Least Concerned species, and one Data The Reptile Database. Available from http:www.reptile Deficient species (International Union for Conservation database.reptarium.cz [Accessed 20 August 2015]), but of Nature 2015). Although both conservation only a single endemic skink is found in Sri Lanka: Dasia assessments used the same IUCN Red List criteria, the haliana (Nevill 1887; Fig. 1). Although the taxonomy national assessment is based on a greater volume of and phylogenetic relationships of Dasia haliana (Haly's literature and expert knowledge of Sri Lankan field Tree Skink) are well established (Deraniyagala 1953; biologists and thus may reflect more accurate assessment Wickramasinghe et al. 2011, Harikrishnan et al. 2012; of species endangerment than the IUCN Red List Chandramurthi and Amarasinghe 2015), we are not (Gärdenfors et al. 2001). aware of any long-term, field-based studies across a Skinks are largely microcarnivores that occupy a broad geographic region that have focused on habitat diverse array of fossorial, terrestrial, and arboreal associations. Dasia haliana is a rare species restricted to habitats. For instance, basal genera such as Chalcidoseps the low country intermediate zone and the lowland dry and Nessia are largely fossorial and Lankascincus are zone, and it appears to be relatively common in the latter terrestrial and sub-fossorial, whereas more derived (Adithya 1968; Samarakoon 2004; de Silva et al. 2005; Copyright © 2016. Suranjan Karunarathna 272 All Rights Reserved. Herpetological Conservation and Biology FIGURE 1. Known color variation or color morphs of Dasia haliana in Sri Lanka: (a) female from Karandagolla forest in 2010, (b) male from Mihintale forest in 2014, (c) sub-adult from Giritale forest in 2012. (Photographed by Dushantha Kandambi [a,b] and A. Jayasooriya [c]). Somaweera and Somaweera 2009; Karunarathna and bioclimatic zones of Sri Lanka during different seasons Amarasinghe 2011). Currently, this species is for 10 y (2004–2014). We surveyed different types of categorized as Near Threatened in the national Red List habitats in protected and unprotected forests, well- of threatened species (Ministry of Environment 2012). shaded monasteries, and home gardens located at the According to published literature, D. haliana has been ecotone of the above bioclimatic zones. In a given mostly recorded from northern, eastern, and north- survey site, we actively searched an area of 10 ha, central parts of Sri Lanka (Deraniyagala 1931, 1953; thoroughly examining the arboreal habitats such as tree Taylor 1950; de Silva et al. 2005; Somaweera and trunks, foliage, rock outcrops, as well as fossorial Somaweera 2009). In this research, we investigated the habitats such as leaf litter, downed woody debris, and distribution, habitat use, behavior, and ecology of D. earthen crevices. We visited sites during the morning, haliana based on field observations, experiments, and evening, and night, before and after the sunset (0700– published literature. 1500, 1600–1900, 2000–2400). The survey time was determined based on the active period of the focal MATERIALS AND METHODS species. In addition to our field observations, we examined museum specimens (National Museum of Sri Field work and data collection.—We surveyed the Lanka, Colombo), consulted other herpetologists, focal species, D. haliana, using 158 random field visits interviewed local people on their opportunistic island-wide, across both dry and intermediate observations, and read all available literature. 273 Karunarathna et al.—Ecology of Dasia haliana. TABLE 1. Current distribution records and habitat data of Dasia haliana in Sri Lanka. District Closest city/town Coordinates (N & E) Elevation (m) Habitat types Climatic zones Ampara Buddhangala 07°20'11.75" 81°42'34.58" 28 Dense forest Dry Ampara Kekirihena 07°30'27.02" 81°19'59.06" 83 Forested home garden Dry Ampara Hulannuge 06°54'54.39" 81°41'26.24" 48 Dense forest Dry Ampara Kudumbigala 06°40'12.03" 81°44'40.14" 64 Dense forest Dry Puttalam Kalivillu 08°28'55.97" 79°56'26.33" 16 Dense forest Arid Anuradhapura Mihintale 08°20'58.14" 80°30'53.16" 174 Dense forest Dry Anuradhapura Jethawanaramaya 08°21'11.37" 80°24'18.00" 81 Dense forest/ monasteries Dry Anuradhapura Eppawa 08°08'43.52" 80°24'51.17" 48 Forested home garden Dry Matale Pidurangala 07°58'02.20" 80°45'19.95" 195 Forested home garden Intermediate Matale Kandalama 07°56'58.47" 80°43'31.13" 298 Forested home garden Intermediate Matale Sigiriya 07°57'01.46" 80°45'42.12" 225 Dense forest/ monasteries Intermediate Matale Pitawala 07°32'50.61" 80°45'17.15" 820 Dense forest Intermediate Matale Thelgamuoya 07°32'11.64" 80°46'21.17" 496 Dense forest Intermediate Polonnaruwa Kawudulla 08°13'28.00" 80°56'42.61" 97 Dense forest Dry Polonnaruwa Giritale 08°00'02.47" 80°35'37.44" 131 Agriculture Dry Polonnaruwa Angammedilla 07°54'29.10" 80°54'44.72" 128 Dense forest Dry Polonnaruwa Minneriya 08°01'49.94" 80°49'59.09" 122 Dense forest Dry Polonnaruwa Dimbulagala 07°51'20.54" 81°07'45.19" 127 Forested home garden Dry Badulla Ulhitiya 07°28'40.62" 81°06'13.11" 377 Dense forest Intermediate Badulla Karandagolla 06°49'36.04" 81°05'41.67" 425 Dense forest Intermediate Hambantota Sithulpauwa 06°23'23.76" 81°27'08.91" 54 Dense forest/ monasteries Arid Hambantota Akasa-chaithya 06°20'33.71" 81°27'48.59" 47 Dense forest Arid Monaragala Nilgala 07°12'13.59" 81°19'29.85" 218 Dense forest/ monasteries Intermediate Monaragala Heenoya 06°30'29.98" 81°08'12.71" 85 Dense forest Dry Monaragala Pokunutenna 06°34'31.22" 80°53'52.53" 128 Dense forest Dry Monaragala Agunukolapalessa 06°27'31.74" 81°01'52.39" 149 Dense forest Dry During the field survey, we made notes on many of 60 mm. We placed three pieces of dry coarse woody aspects of the natural history of the focal species and debris (150–200 mm long, 40–80 mm wide, and 20–40 habitat characteristics of the survey sites. We recorded mm deep) horizontally on the soil. We placed three tree the ambient temperature with a standard thermometer, branches (300–400 mm long) vertically inside the substrate temperature with N19 Q1370 an infrared mesocosm. We intermittently noted the habitat thermometer (Dick Smith Electronics, Shanghai, China), occupancy of all individuals for 14 h per day for the and relative humidity and light intensity with a QM 1594 entire duration of the experiment. All daily observations multifunction environment meter (Digitek Instruments were done during 1600–1900 and 2000–2400, which Co., Ltd, Hong Kong, China). We measured elevation was the same as our field observation period. using an eTrex® 10 GPS (Garmin, Johannesburg, South Africa).