Goniurosaurus catbaensis, Ziegler, Truong, Schmitz, Stenke, Rosler, 2008

Ngo, Hai Ngoc, Le, Tuan Quang, Pham, Minh Le, Nguyen, Truong Quang, Le, Minh Duc, Schingen, Mona van & Ziegler, Thomas, 2019, First record of the Cat Ba Tiger Gecko, Goniurosaurus catbaensis, from Ha Long Bay, Quang Ninh Province, Vietnam: microhabitat selection, potential distribution, and evidence of threats, Amphibian & Reptile Conservation (e 183) 13 (2), pp. 1-13 : 6

Goniurosaurus catbaensis in Ha Long Bay, Vietnam

59) slightly higher than mean substrate temperatures of 26.02 ± 1.5 °C (22.2–28.2 °C, n = 28, Table 4). Recorded relative humidity at microsites ranged between 70–99% (mean 84.9 ± 6.99%, n = 52).

A vast majority of lizards was found on limestone cliffs (62%), followed by rocks (28%), while only a few specimens were found on the forest floor (5%), branches (3%), or sand (2%) [ Fig. 4A ]. A significantly lower number of lizards was encountered inside compared to outside of limestone caves (26.9% vs. 73.1%, respectively). Goniurosaurus catbaensis selected spots with a mean canopy coverage of 95.2 ± 9.6% (n = 63, Table 4). Adult specimens (non-gravid) were found at average heights of 1.15 m (n = 38), while juveniles and gravid females resided at significantly lower heights of 0.28 m (n = 4) and 0.41 m (n = 12), respectively (t = 2.82, df = 48, P <0.05; t = 2.06, df = 40, P <0.05, Fig. 4B ). A majority (about 77.4%, n = 48) of lizards was resting during the surveys, while only a few individuals (n = 14) were found actively foraging.

Suitable habitats for G. catbaensis were predicted to encompass a majority of small islands belonging to Cat Ba Island and Ha Long Bay , and include a wider area on the coastal mainland of Quang Ninh Province, where no surveys have been conducted so far ( Fig. 5 ) .

Trade: Trade in living tiger geckos has been frequently recorded by our team in local pet markets from Hai Phong and Ho Chi Minh cities, as well as on Facebook since 2015. Interviews with two local traders in Ho Chi Minh City revealed that they pay for local villagers living within the species’ distribution range to collect live tiger geckos during the non-hibernation season, confirming the wild (rather than captive-bred) source of traded animals. The dealers reportedly received individuals of three tiger gecko species, namely G. huuliensis , G. luii , and G. catbaensis , collected in April 2015. Among those, three individuals of G. huuliensis (one male and two females) were allegedly collected by a local hunter from Huu Lien Nature Reserve, Lang Son Province. Two local collectors from Cao Bang Province reportedly collected six individuals (three males and three females) of G. luii in northern Vietnam and another local hunter collected two couples of G. catbaensis . These 13 wild caught tiger geckos were transferred to pet markets in Ho Chi Minh City, southern Vietnam, in April 2015.

Human impacts on the habitat: Tourism activities in the region have dramatically increased in the past, and likely exerted enormous pressure on wild G. catbaensis populations. Events organized by tourism companies regularly took place in at least two caves located within the UNESCO World Heritage Site. According to interviews with fishermen, daily excursions to the caves are scheduled to start at 7:30 PM and end around 11:00 PM. On these occasions, tourists dine in brightly lit caves before returning to their tour boats ( Fig. 6B ). As a consequence, wildlife is likely to be disturbed by the candle light, noisy sounds, and waste left by the tourists.

Figures

Fig. 4. (A) Substrate selection of Goniurosaurus catbaensis. (B) Box plots of perch heights of different age classes and sexes.

Fig. 5. Predicted habitat suitability for Goniurosaurus catbaensis in Vietnam.

Fig. 6. Potential threats to Goniurosaurus. (A) Flooding of Viet Hai Commune in August 2015. (B) Tourist event in a cave within the UNESCO World Heritage Site on Ha Long Bay. Photos H.N. Ngo.