New insights into the habitat use and husbandry of crocodile lizards (Reptilia: Shinisauridae) including the conception of new facilities for Vietnamese crocodile lizards Shinisaurus crocodilurus vietnamensis in Vietnam and Germany

Abstract

The Crocodile lizard Shinisaurus crocodilurus is a popular reptile species in the pet trade and has been regularly kept in terrariums by hobbyists since the 1980s. Recent integrative taxonomic research revealed the Chinese representatives to be morphologically, genetically and ecologically distinct from Vietnamese populations, which occur in alarmingly low population sizes. All extant populations are threatened by habitat destruction and poaching for the pet trade. Thus, it will be crucial to manage the Vietnamese and Chinese subspecies separately as different conservation units, both to maintain their genetic integrity and to adjust appropriate husbandry conditions in the frame of ex situ conservation programmes. For this reason, we provide a topical review of microhabitat use of the newly described subspecies from Vietnam – the Vietnamese crocodile lizard Shinisaurus crocodilurus vietnamensis – based on recent field work as well as husbandry experiences at the Me Linh Station for Biodiversity in North Vietnam. We further compare our new findings with the data available for the nominate subspecies from China. Based on our current knowledge, we update existing minimum husbandry requirements in Germany and elaborate different husbandry parameters for both subspecies. Furthermore, we introduce new husbandry protocols and facility designs for the Vietnamese subspecies both at Me Linh Station for Biodiversity and at Cologne Zoo, Germany.

Climate Change and Dispersal Ability Jointly Affects the Future Distribution of Crocodile Lizards

“…Contemporary precipitation patterns can be used as a reflection of historical land-use changes [ 87 ]. Crocodile lizards are habitat specialists requiring high quality habitats [ 53 , 64 , 91 ]. Their habitat is dominated by broad-leaved forests with a veg-etation cover of >80% [ 65 ], which effectively blocks out UV rays and creates a microclimate with relatively stable temperatures.…”

“…However, they are also defined by anthropic actions ( Figure 6 b) and their effects on ecosystems ( Figure 6 c). Vegetation, topography, and hydrological conditions influence the growth, development, reproduction, and survival of the crocodile lizard [ 51 , 52 , 53 , 65 ], while human land use and harvesting directly influence wild populations and the quality of remaining habitat within the crocodile lizard’s range [ 49 ]. All these variables, by themselves or in combination, show a strong effect on the spatial distribution patterns of crocodile lizards.…”

“…The crocodile lizard is a diurnal lizard that spends 69% of its total active behavior time in a sedentary position [ 51 , 52 ]. They require constantly cool water and adjacent terrestrial areas [ 51 , 52 , 53 ]. Additionally, the occupied temperature niche of crocodile lizards is narrower compared with the environmental fundamental niche, with the temperatures of the animal being generally cooler compared with environmental temperatures [ 53 ].…”

“…Additionally, the occupied temperature niche of crocodile lizards is narrower compared with the environmental fundamental niche, with the temperatures of the animal being generally cooler compared with environmental temperatures [ 53 ]. Chinese crocodile lizards hibernate from October to April and initiate hibernation at temperatures between 8 and 11 °C while Vietnamese crocodile lizards initiate hibernation at mean temperatures of 17.5 °C in December and start becoming active without a pronounced increase in temperature in March [ 53 , 54 , 55 ]. Reptiles are particularly vulnerable to heat stress because they have to regulate their body temperature behaviorally [ 56 , 57 ].…”

Potential impact of land‐use change on habitat quality in the distribution range of crocodile lizards in China

“…At the same time, crocodile lizards have high requirements for water quality in their habitat. In Pham, et al, 2014;Ziegler et al, 2019). Furthermore, the water ranges from neutral to relatively acidic conditions with pH values ranging from 4.5 to 7.37, while pH values of 6.5 were measured in Dayaoshan Nature Reserve, Guangxi, China (DYS; Long et al, 2007;van Schingen, Pham, et al, 2014).…”