Field Surveys Suggest Biennial Reproduction Cycle and Competition-triggered Dispersal of the Endangered Chinese Crocodile Lizard

The endangered Chinese crocodile lizard(Shinisaurus crocodilurus)is a habitat specialist living in streams of mountain forests in southern China and northern Vietnam.Conservation efforts are increasing for recovering its wild populations.However,the growth,reproduction,and dispersal ability of crocodile lizards in the wild are largely unknown.We conducted field surveys of the crocodile lizard population in Daguishan National Nature Reserve,one of the largest extant wild populations of crocodile lizards,for three consecutive years in Guangxi,China.We found that crocodile lizards generally reach sexual maturity at the age of 2.5 years in the wild.Unlike most viviparous lizards,which reproduce annually,the crocodile lizard shows a biennial reproductive cycle.The number of observed juveniles and subadults fluctuated between years,whereas that of adults remained relatively stable.Non-adults had longer three-year dispersal distance than adults.Crocodile lizards showed preference for backwater pools in the stream.Competition for better resources may be the main trigger for dispersal.