Study On The Ecology Of Chinese Softshelled Turtle (Pelodiscus Sinensis) In The Yellow River Beach,Shaanxi Province,China

Chinese softshelled turtle(Pelodiscus sinensis)distributed in East Asia,from the Amur and Ussuri Rivers in the Far East of Russia through Korea,Japan,and eastern,central,and southern China to southern Vietnam.P.sinensis has been listed as vulnerable species by IUCN due to the populations of this turtles have been declining at rapid rates.Ecological research is the foundation of species conservation and management.Despite this turtle was widely distributd and its close association with human beings,the research on their field ecological is still rare.Therefore,we investigated the populations density,habitat selection,movements,home ranges and diet of P.sinensis in the Yellow River,northwestern China,from October 2016 to September 2018.This study is the first to focus on the ecological research of P.sinensis and hence contributes invaluable knowledge on the species natural history which is highly needed for effective conservation efforts.1.Populations density of P.sinensis.Local interview and cage trapping were performed to investigate their population distribution and density of P.sinensis.Twenty-three turtles were trapped in main channel of Yellow River,21 captured in surrounding wetlands through 1538 cage days'effort.So,the relative population density of P.sinensis was 0.02861 per cage day and the catching population density of P.sinensis was 12.9/km~2 and 52.5/km~2 at main channel of Yellow River and surrounding wetlands respectively.Moreover,female-male proportion of all captured P.sinensis is 1:1(23:21),and the analysis results show spatial distribution pattern of P.sinensis is aggregated.Local interview show that poaching is rampant and this turtle have been declining at rapid rates in recent years.2.Habitat selection,Movements and Home ranges of P.sinensis.Thirteen adult P.sinensis(5 males and 8 females)were monitored with radio-transmitters.The mean linear range size(LR)was 440.44±161.27 m,the mean river channel area was 1.98±0.72 ha,the mean minimum convex polygon(MCP)size was 1.36±0.65 ha,the mean 95%kernel density estimator(95%KDE)measured 0.84±0.51 ha,with a core area(50%KDE)of 0.30±0.20 ha.The LR/MCP/95%KDE/50%KDE was not significantly different between the sexes and no significant relationship with either SCL or BM.Home range overlap occurred both within and between genders,on average,individual MCPs overlapped with those of 5.8 other individuals,individual KDEs with those of 6.1other individuals,and core areas with those of 5.1 other individuals.Movements of P.sinensis averaged 35.48±17.69 m/d SD for males and 42.82±17.88 m/d SD for females,and there was no significant difference between sexes and no significant correlation between movements and body size.However,there was significant difference between sexes during nesting season.May is the most active month with an average daily movement for all turtles of 58.6±6.1m/d SD and January is the least active month(mean moved0.4m/d).P.sinensis selected the relatively shallow(<2.0m),slow-moving pools covered by common reed,and rarely selected the areas with a hardened riverside.3.Diet of P.sinensis.In August 2018,24 stomach content samples were collected from wild-caught P.sinensis individuals from natural habitats in the middle confines of the Yellow River,China.The samples were analyzed and included:ten juveniles,eight sub-adults and six adults.The species diet was noted to be primarily omnivorous and comprised 23 prey taxa classified into nine groups:plant(4),fish(1),frog(1),earthworm(1),insect(9),mollusk(3),shrimp(2),and other miscellaneous items.There was significant difference in diet composition among the three age groups.