Reproductive Ecology of the Kandyan Day Gecko, Cnemaspis Kandiana, in Gannoruwa Forest Reserve
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08.2008 ReproductiveJ.Natn.Sci.Foundation ecology of Sri Cnemaspis Lanka 2009 kandiana 37 (1):13-22 13 RESEARCH ARTICLE Reproductive ecology of the Kandyan Day Gecko, Cnemaspis kandiana, in Gannoruwa Forest Reserve Ruchira Somaweera Department of Zoology, Faculty of Science, University of Peradeniya, Peradeniya. Revised: 10 April 2008 ; Accepted: 18 August 2008 Abstract: Breeding habitats and environmental conditions anything is known about the biology of the various preferred by Cnemaspis kandiana, its oviposition and species. The reproductive ecology of Cnemaspis is reproduction aspects, its interactions with other species in the interesting because of the communal nesting exhibited by nesting habitat, and the mode of oviposition were investigated at the Gannoruwa Forest Reserve, Sri Lanka, during fortnightly some species. To date only ten species, viz., C. alwisi, C. field surveys from June 2005 to January 2006. Eleven egg clivicola, C. kallima, C. kandiana and C. upendrai from clusters in five caves at Gannoruwa were sampled and data Sri Lanka12,13, C. baueri from West Malaysia6, C. indica on the environmental conditions inside the caves, number from Western Ghats14, C. cf. indraneildasii from India15, of hatched and unhatched eggs, hatchlings, adults and other C. kendallii from Singapore16 and C. mysoriensis from faunal species in the nesting habitat recorded. Six eggs were India17, have been reported to exhibit communal nesting. incubated in the laboratory. At the nesting sites, ambient temperature varied from 23-30 ºC and light intensity from However, at least five other Indian species of the genus 0-350 lux. The eggs were predominantly laid as pairs (on 85% resort to communal nesting (personal communication, occasions) suggesting that C. kandiana has invariant clutch Sayanthan Biswas), with the possibility of some of these size. The hatched and unhatched eggs at each location varied exhibiting interspecific communal oviposition15. from 1 to over 100, though the maximum number of unhatched developing eggs found at a given time was 18, i.e., a cluster size to vary from 1-18 eggs. Eggs tend to hatch in pairs, after It has been reported on the possibility of more than 13,18 an apparent incubation period of 39-58 days. The hatchlings one female of C. kandiana laying eggs at the same site . had a total length of 23.5-25.8 mm. No interaction with regard Some subsequent authors19 have referred to the above to reproduction was found between C. kandiana and any other same study but without providing any new information. animals at the breeding sites. The egg-laying in this species Ratnayake 20, de Silva et al.21 and Manamendra-Arachchi is probably a combined effect of site fidelity of a female and 12 communal nesting. This might be due to relative scarcity of et al. other study graphs have provided brief notes and preferred habitats in the study area. a photograph of communal nesting sites under the bark of a tree and among rocks12,20-21. Keywords: Clutch size, cnemaspis kandiana, communal nesting, Gecko, reproduction, Sri Lanka. The present study addresses four issues in C. kandiana, i.e. (1) the breeding habitat and its INTRODUCTION environmental correlates, (2) some aspects of its oviposition and reproduction including incubation period, Oriental Dwarf or Day geckos of the genus Cnemaspis clutch (considered here as the total number of eggs laid Strauch (1887) are represented by ~70 species in South and Southeast Asia, with additional forms in by a single female at a single time) cluster (total hatched tropical Africa1-12. They are represented in Sri Lanka + un-hatched eggs at the same location) sizes, and size of by 21 member species12. Though the taxonomy of these hatchlings, (3) interactions with other species at nesting members has received considerable attention, hardly sites, and (4) the biological basis of communal nesting. *JournalCorresponding of the National author ([email protected]) Science Foundation of Sri Lanka 37 (1) March 2009 14 Ruchira Somaweera (in lux using a Lutron LX 101 Lux meter) at mid-depth of METHODS AND MATERIALS the caves was recorded only during a single visit. At least Study species: Originally described as Gymnodactylus a single night visit was made to each cave. Additionally, kandianus, the species C. kandiana has served as a random searches for geckos were done on tree trunks, catchall species in the region. Until recently, C. kandiana buttresses, among leaflitter, under stones and logs at was considered to be a widespread species in Asia. Some the GFR, Udawattakele in Kandy and lower Hantana at authors described C. kandiana as widespread in southern Peradeniya. India, Sri Lanka and ranging from the Andaman Islands b) eggs: Representative clusters were selected for to Indonesia22. However, based on recent studies, it is observation in all the caves and the number of eggs considered that C. kandiana sensu stricto is restricted to (unhatched + hatched) in those clusters were counted, the mid-central hills of Sri Lanka, specifically the moist numbered with a 2B lead pencil and photographed using forests of the Central Province between 400-700 m.s.l., an Olympus C740 digital camera. Representative eggs with rainfall of >2,500 mm per year12. Furthermore, from different clusters were measured using Mitutoyo C. andersonii, C. malabarica and C. wicksii previously digital Vernier callipers (to the nearest 0.05 mm). synonymized are now considered as valid species12. Depending on the rate of oviposition (frequency of Study site: The site of the study was the Gannoruwa Forest addition of new eggs), rate of hatching (considering Reserve [GFR] (7º 17’ N, 80º 36’ E) in Kandy District of incubation time, synchrony and asynchrony of hatching) the Central Province. The mean annual temperature is and maximum number of unhatched eggs present at a given time (considering the cluster and clutch sizes), it 24.1 ºC with lowest temperatures in January and highest was determined whether the particular cluster represented in April. Mean annual rainfall is 2131 mm, derived from a communal nesting site or a non-communal nesting site both the north-east and south-west monsoons23. The within the study period. area belongs to the Kandy-Upper Mahaweli floristic zone24 and Intermediate Wet Evergreen Forest ecotone23. c) adults: Whenever possible adults were caught manually, The GFR contains several medium-sized and numerous sexed, measured as above and marked using a technique small-sized talus (boulder) caves, i.e. found at the base of similar to that used by Werner & Chou 16, where a ~5x5 a cliff or slope and usually the result of a rock-slide type mm piece of 3M Scotchlite 8830® silver marking film action, and crevice caves, i.e. found where a cliff face has with a serial number written on it using a black fine pulled away from the stable rock face, creating a crack felt pen was pasted on the dorsal side between the hind or crevice. Five study caves were selected, four near the limbs. The marked animals were released where they had Dankella entrance and the other above the Bulawaththa been caught and the markings were clearly reflected and entrance, based on the presence of egg clusters, nature were visible when a light beam from a head-torch was and size of the cave, surrounding vegetation and ease of directed. Some individuals were photographed in situ. access. No geckos were killed or harmed in this study. Field sampling: d) other animals in the caves: Presence of other vertebrates a) the caves: The study included 14 consecutive sampling and invertebrates inside the caves was recorded and sessions conducted between 18 June 2005 and 29 January observations (such as feeding) were made to investigate 2006. The GFR was visited fortnightly during each month whether there were any interactions between them and except in June 2005 when only a single visit was made. A C. kandiana. Three adult individuals of the endemic typical sampling session lasted from ca 0700-1400 h. The mollusk Ratnadvipia irradians (which was very common order of visiting the caves was rotated during subsequent inside the caves) collected from caves 1, 3 and 4, were visits to reduce the bias of time of sampling. During kept in captivity in separate jars for a week and they the initial visit for detailed sampling, the following were offered broken parts of egg shells collected from information was recorded for each cave. 1) GPS the caves to observe whether they fed on them. location (Using a eTrex Venture GPS), 2) maximum Ex-situ studies: height and width of the cave entrance, and maximum depth of the cave (using an Freemans 5) m flexiruler), Two eggs from each of three representative egg clusters 3) geographical orientation of the opening (using an found in three caves were incubated under artificial Silva® Sweden Type 4 compass), 4) ground substrate, conditions. The two eggs collected on 12 June 2005 0 and 5) surrounding vegetation. Temperature (in C using (during the reconnaissance survey) from cluster 1 of a field thermometer) at mid-depth of each cave was cave 2 had not been present in the site on 11 June 2005, recorded during all subsequent visits, but light intensity showing that they were laid between the two sampling March 2009 Journal of the National Science Foundation of Sri Lanka 37 (1) Reproductive ecology of Cnemaspis kandiana 15 sessions. Eggs from different caves were placed on tissue from 20-350 lux during the day. Light showers were paper in separate glass jars with the mouth covered by noted in the area during July, August, December in the a fine mesh. The bottles were placed in a shady place year in 2005 and in January 2006. inside a room with an ambient temperature varying between 24±2 ºC.