The Early Stage Of The Chinese Giant Salamander Breeding Behavior And Its Relationship With Environmental Factors At Night

Chinese giant salamander (Andrias davidianus) that is listed in the State Class II Key protection and also is the largest amphibians in the world. Because it is so ancient animal in evolution, and is referred as live fossil in China. In this paper, the Chinese giant salamander in imitated-natural habitat of the Qinling Mountains as the research object, and the behavior, the nocturnal rhythm and the environmental factors of the Chinese giant salamander were studied from July to August,2011during the pre-reproductive period respectively used all occurrence recording method, adlibitum sampling, instantaneous and scan sampling and target objective observation method, which in order to find out the relationships between basic behavior, nocturnal rhythm of the Chinese giant salamander and environment. The aims of these studied were to provide some datum for behavior research, conservation and reproductive of the Chinese giant salamander. The main results and conclusions were as follows:1. The results showed that Chinese giant salamander moved out at7:30PM, their activities reached the peak in9:00PM and remained to1:30AM of the next day. After6:30AM, all Chinese giant salamanders returned to the den. And also, activities numbers of the Chinese giant salamander reached peak value about10:00PM. There were significant difference in nocturnal number between male and female Chinese giant salamander, while there was no difference in nocturnal number between the adult and the subadult. In different weather, activities numbers and nocturnal rhythm of the Chinese giant salamander was substantial same, activities peak appeared9:30PM and2:30AM of the next day. The Spearman Rank Correlation test found that illumination intensity and water temperature were closely correlated with the nocturnal number of the Chinese giant salamander in different weather. The relationship between water temperature, illumination intensity and activities numbers of the Chinese giant salamander can be adequately expressed in the different weather by the non-linear equation. The Chinese giant salamander began to come out or be back when the illumination was685-1431Lx and the relative illumination was3%. The peaks of activities occurred when the water temperature was17.1-18.4℃(2hours after the illumination was0Lx).2. This study demonstrated that the illumination and water temperature affected the nocturnal activity rhythm of the Chinese giant salamander during the pre-reproductive period. The illumination was the key factor which controlled the activities outside of den, and the water temperature was the main factor to determine the activity peaks. Besides, both the adult and the subadult came out for feeding during the pre-reproductive period. As for different sex of the Chinese giant salamander, the male must acquired large amounts of food to store abundance nutrition and energy in order to protect the zygote, on the other hand, the female stored a lot of eggs, which resulted in weight increasing. Thus, the female moved out less than male.3. We recognized12different behaviors including feeding, resting, creeping, swimming, head exposing, breathing, gaping, washing behavior, sand-pushing behavior, courtship behavior, social behavior, fighting behavior and so on. These behaviors were divided into five basic types which included feeding, resting, moving (creeping, swimming), reproductive behavior (washing, sand-pushing, courtship), others behavior (social behavior, fighting behavior). Feeding, resting, moving, reproductive behavior, others behavior were basic behavior that make up50.20%,33.39%,6.34%,9.62%and0.45%, of the nocturnal time budget, respectively. No significant differences in feeding and others behavior between male and female were found, while significant difference existed in resting, moving and reproductive behavior using Wilcoxon test. No difference in others behavior between adult and subadult was present, while significant difference occurred in feeding, resting, moving and reproductive behavior using Mann-Whitney U test. Illumination intensity did not produce influence on behavior, but light intensity during the pre-reproductive period showed its influence on behaviors, water temperature closely correlated with the resting behavior and the feeding behavior, while water temperature no correlated with moving, reproductive behavior and other behavior by Spearman Rank Correlation test. In nocturnal rhythm of basic behavior, the Chinese giant salamander had two resting peaks before and after feeding peaks.4. This study demonstrated that imitated-natural habitat of the Chinese giant salamander was similar to natural environment because of imitated-natural habitat provided the approximate element needed in natural environment. The Chinese giant salamander not only performed behaviors of high inelasticity that creeping, swimming, feeding, resting, breathing, gaping, but also performed behaviors of elasticity that head exposing, washing behavior, sand-pushing behavior, courtship behavior, parent care, social behavior in the imitated-natural habitat.