| Tibetan fox (Vulpes ferrilata), a typical plateau species, is a small sized canid of the Vulpes genus, which only distributes on the Tibetan plateau in* China, Nepal and northern India, between 3000 and 5300m of altitude. However, little information about the biology and ecology of this species is known that IUCN cannot give out effective conservation strategy. Moreover, although, the Tibetan fox is known as the definitive host of echinococcoses which are very severe zoonoses and endemic in the pasturing area west China, the exact function and the degree about how the Tibetan fox affecting the transmitting of the disease are still remained unknown. Hence, the field ecological research will bring the conservation biology and parasitology the fundamental and imperative information.We surveyed Shiqu County, west Sichuan Province from 2001 to 2004, including Derongma, Sexu and Eduoma 3 villages. This region is a large flat area with gently rolling hills. Line transect was used when doing systematical sampling. Tibetan fox den structure and den habitat were studied. Based on the result of these researches, habitat selection models were constructed. By observing the Tibetan fox behaviour, we also researched the daytime activity rhythm and evaluated the population size in the research site. Conservation status of Tibetan fox was studied based on the research of the habitat and the evaluation of the poaching pressure. Finally, we dissected Tibetan fox carcasses to realize the infection rate of echinococcosis in Tibetan fox population. By consulting references of the past 20 years, we discussed the important function of foxes in the transmitting of echinococcosis. The results are listed as follows:1. The mean entrance number of Tibetan fox dens are 1.795 ± 1.809 (n = 156) . Multi-entrance dens (n = 47) had significantly higher distribution of position rank on slope than that of mon-entrance dens(n = 109)(Mann-Whitney, U = 1417. P < 0.001). The mean of den width, height and first tunnel length of 91 measured dens are 17.01 ± 2.50 (± SD)cm, 24.91 ± 7.22 cm and 169.98 ± 88.43 cm respectively. Among the 91 dens, 68 were made in soil, 14 in rock and 9 were made in rock and soil. Rock dens had a significantly higher distribution on slope than the other twokinds of dens (x~2 = 10.227, P = 0.006). Dirt ramp could be found in 71.6% of 74 examined dens. Den entrance exposure had no concentration on mean angle (Rayleigh, z = 0.898, n = 201, P > 0.05), but slope direction concentrated significantly on the mean angle 249.9±77. 1 ° (± SD) (Rayleigh, z = 7.907, n = 201, P < 0.05). Entrance exposure and slope direction had no correlationship (Hotelling, F = 5.365, n = 201, P < 0.05). However, the first tunnel obliquity correlated with the slope degree (t = 0.35, n = 116, P > 0.05). We did not find any fox dens on the plain area. During our filed research, 4 breeding dens were found totally, which were made in soil with the slope direction from 220 to 320°.2. Principle components analysis (PCA) and Logistic regression model (LRM) were introduced in the analysis of 133 Tibetan fox den habitat plots. The first 3 components in PCA had the cumulated contribution above 75%. Among them, food and water resource factor (containing variables "water resource distance" and "pika dens number") was the most important factor. Position factor ("slope degree" and "position on the slope") and Concealment factor ("vegetation type") were the second and third factors. LRM revealed that "slope direction", "position on the slope" and "vegetation type" are the 3 variables significantly influencing the den habitat selection of Tibetan fox. In conclusion, the ideal den habitat of Tibetan fox should be the area with the water distance between 500 and 1000 m, and with the distribution of pikas in the same area. Tibetan fox dens should be distributed on the gentle slope with lower position and sunny or half sunny slope direction. In addition, low and open vegetation is also imperative.3. Pika dens could be found significantly more in the abandoned Tibetan fox...
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