Spatio-temporal Distribution And Habitat Use Of Steppe Lizard (P.Frontalis) And Its Role In Pest Control

Spatio-temporal distribution, habitat selection and population characteristics are all significant issues in the study of population ecology. By investigating distribution, population status and habitat use, we can get knowledge of the role of animals in the ecosystem. As predators, reptiles affect the components and community structures of their prey (e.g. insects) in their habitat, and then play an important role in pest control.Steppe toad-headed lizard (Phrynocephalus frontalis) widely distributed in the grasslands and semi-desert regions at the northern of Yin Mountain in Inner Mongolia of China. In order to learn the population parameter, habitat use and the function in pest control, I studied daily activity rhythm, distribution pattern, population parameters, habitat selection, feed intake and pest control of Steppe toad-headed lizard at Hunshandak Sand Land in China. The main results are as follows:(1)Steppe toad-headed lizard is a diurnal animal. By adopting the method of route and quadrat survey, I observed and recorded the initial time, finish time, and the peaks of activities in the steppe toad-headed lizard. I found that there are two peaks of activity of the lizard in a day: one was from 9:00 to 13:00; another was from 15:00 to 17:00.I supposed that the activity intensity of this lizard was depended on some environmental factors (e.g. external temperature).(2)The Clustered Indices and the Rule of Nearest Neighbor showed that lizards were clustering. The distribution pattern of this lizard was quadrat-sampling dependent. The cluster was determined by environment when the sampling quadrat was smaller than 20×20m, while the cluster was co-determined by environmental factors and characteristics of lizards when the sampling quadrat was larger than 20x20m. I suggested that steppe toad-headed lizards tend to aggregate into the suitable habitat patches in the desert.(3)By mark-recapture method, I investigated the population density of steppe toad-headed lizard in 15 plots. According to the density of the lizards (more or less than 0.1 individuals/m2), I divided the plots into two types:more lizards (Ⅰ) and less lizards (Ⅱ). Based on individual body length, I divided all the samples into three age groups:adult (76.18-112.56mm), subadult (56.02-75.32mm), and juvenile (46.34-55.98mm). I calculated and analyzed the age structure and sex ratio of the lizard population. The results showed that the age structure of Steppe toad-headed lizard population associate with the changes of reproductive and growth cycle. Female dominated the population size of steppe toad-headed lizard in this area. The sex ratio (♀:♂) was nearly 2:1. (4) I monitored the vegetation coverage, soil moisture, surface sand distribution, total quantity of preys in different seasons and abundance of invertebrates of the samples selected and found that the quantity of preys in June (P=0.001<0.01) and distribution of surface sand were significantly associated with the density of steppe toad-headed lizard. The size of sand in 0.5-2mm was significantly positively correlation (1-2mm, P=0.000<0.01; 0,5-1mm, P=0,000<0,01); less than 0.25mm was significant negative related to the density (P=0.001<0.01). On top of this, the rest of the factors associated with the density of the sand lizard were not significant.(5) I analyzed the diet and feed intake to determined the pest control efforts of the steppe toad-headed lizard by the method of stomach contents analysis. The results showed that the lizards preys mainly on the insects of Coleoptera (the percentage of individuals=32.6%; frequency= 96.3%) in summer, it makes up a third part of their total food. The next to the Coleoptera is the Hymenoptera, which accounts for more than half (percentage of individuals score=56.39%; frequency=81.48%). In autumn, the main advantages is the Hymenoptera (the percentage of individuals=50.83%; frequency=93.10%), the insects of Hemiptera was followed (the percentage of individuals=34.58%; frequency=75.86%). There were no significant difference among the individuals of different age and sex of the population. In the diet of steppe toad-headed lizard, the pest was dominant. In summer, the intensity of predatory beneficial insects was increased and more harmful types in predation in autumn, however.In sum, spatio-temporal pattern of activity of steppe toad-headed lizard were affected by external temperature, food availability and sand substrate. Furthermore, the spatial distribution pattern of the lizard also varied with the size of sampling quadrat. Population parameters (especially sex ratio) associated with the reproductive cycle and the phase of development. Predation intensity and the components of preys reflected the role of steppe toad-headed lizard in pest control. Omitting the ratio of pest insects and beneficial insects, steppe toad-headed lizard with high density will benefit their function in pest control.