Comparison Of Tibetan Fox's Home Range Estimators And The Influence Of Major Food On The Home Range Character

Tibetan fox (Vulpes ferrilata) is a kind of small Canids which has strong activity and large scope of activity area, and mainly distributes in Qinghai-Tibet Plateau such as 3500 meters above.The Tibetan fox would like to stay in the alpine meadow in the open grassland. The major prey of Tibetan fox is Plateau Pika and other Rdents. So Tibetan fox play an important role in keeping banlance of the ecosystem of Qinghai-Tibet Plateau. There is little information about Tibetan fox in biology and ecology by now. In addition, the Tibetan fox is a terminal host of echinococcosis, which is a serious zoonotic parasitic disease. The life history of Tibetan fox and how do they transmit disease in the field are not clear. In order to research the protection of the species and route of transmission of echinococcosis, it is necessary to research Tibetan fox in ecology.The minimum convex polygon (MCP) and the fixed kernel estimator (FKE) are the two methods which are most popular for home range estimation. However, because of the problems like spatial data dependence and extreme data points, the usage of these two methods is limited. We attempted to analyze and compare the results between the two methods, and discussed how to avoid these disadvantages of each method to make the home range estimation more accurate. We documented 352 locations of 7 adult Tibetan foxes in Shiqu County, Sichuan Province and Dulan County, Qinghai Province during 2006 and 2007. Both MCP and FKE were used to calculate the home range area. We found that:(1) when the utility probability percentage was set≤95%, there is no significant difference between results calculated by two methods; (2) although FKE was more robust than MCP, extreme data points influenced the calculation of both the two methods in higher utilization probability percentage (ie,85%-100%); (3) home range size calculated by FKE was influenced significantly by the setting of h which could be determined arbitrarily and the least squares cross validation did not always provide the best evaluation of h. We recommended that both of the FKE and 95% MCP should be used in one home range study. FKE is better than MCP when the autocorrelation of data spatial distribution is not significant. However,95% MCP is the only choice especially when the comparison of the results between different telemetry studies. We recorded activities of 5 ((?) 2, (?) 3) radio-tracked Tibetan foxes in Shiqu County, Sichuan Porvince during 2006-2009. We documented 216 locations during research period. We also investigated the plateau pika(Ochotona curzoniae)density in this area,95% MCP home range area of these 5 foxes are different from 0.67 to 11.59 km2, and their average home range area is 4.64±4.17 km2.The home range area of males are bigger than females. Every fox has overlap home range area with others. Different parts of research area have different average density of the plateau pika: activity area (x=8.09±5.12)> overlap home range area(x= 8.06±4.14)> home range (x= 7.05±4.18)> research area (x= 6.43±4.71). There are no significant difference between activity area and overlapping home range. Tibetan fox has significant selection on food by home range area and activity area; Different food distribution and food selection of the Tibetan fox are important factors whice lead to the overlapping home range.We monitored diurnal activity rhythm of Tibetan fox (SQ05,1(?)) by radio-telemetry from August to September,2009. In order to revealed the hidden cause and biological function of the action, we discussed the influence of plateau pika and temperature on the diurnal activity rhythm of the Tibetan fox. The results showed that: The diurnal activity rhythms of Tibetan fox have significant difference between 6 different time intervals (Chi-Square test, df= 5, P< 0.001), the peak of its activity concentrated on 9:31-13:30 and 17:31-19:30. The highest encountering rate of plateau pika appeared in 7:30-9:30; The lowest encountering rate and the minimum number of pika appeared in 15:31-17:30. The diurnal activity rhythms of plateau pika has no significant difference between 6 time intervals (Kruskal-Wallis test: H(5,n=44)= 3.744, P= 0.587). The diurnal activity rhythm of the Tibetan fox has no significant correlation (Spearman correlation coefficient=-0.143, P= 0.787) with plateau pika, so diurnal activity rhythm of plateau pika has no significant effect on the activity rhythm of Tibetan fox; Temperature has significant differences (Kruskal-Wallis test:H (5, n=348)= 224.727, P< 0.001) between 6 time intervals. The lowest average temperature in daytime appeared in 7:30-9:30, and 15:31-17:30 the highest. There is nonlinear relation between Tibetan fox and temperature (Quadratic curve regression, r2= 0.58, P= 0.272). In daytime, the Tibetan fox's activity rate increased accompany temperature increased gradually. Tibetan fox's activity rate will decreased when the temperature reached a high level. The most comfortable temperature for Tibetan fox activity is 10-16℃. The selection can helps Tibtan fox to avoid energy consumption caused by too hot or cold weather, it maybe the best prey strategy adopted by the Tibetan fox.