3.2 ǀ Differences in habitat utilization
The density of breeding pairs was 72 pairs per km2 in the high disturbance habitat, 50 pairs per km2 in the low disturbance habitat, and 55 pairs per km2 in the natural habitat (Figure 1B, 1C, 1D; Table 2), although none of the differences in breeding pair density were detected among the three habitats are statistically significant (χ2 = 1.14, p = 0.285 between HDH and NH; χ2 = 1.99, p = 0.157 between HDH and LDH; χ2 = 0.119, p = 0.729 between LDH and NH). However, inter-group differences emerged in measurements related to the burrows themselves, with a significant negative correlation between the intensity of human activity and the number of burrows per breeding pair: pairs in HDH dig far more (twice as much as) pair-specific burrows than pairs in LDH (t = 3.63, p=0.000, d.f. = 66) and NH (t = 4.21, p = 0.000, d.f. = 52), furthermore, though not significant (t = 1.83, p = 0.074, d.f. = 46), pairs in LDH also on average dig two more extra burrows than their counterparts in NH (13.39 ± 0.96 V.S. 10.82 ± 0.73). (Figure 3A).
Moreover, average distance between burrows also differs between different habitats: inter-burrow distance of reproductive burrows in the high disturbance habitat is less than that of the other two habitats (t = -3.22, p = 0.002, d.f. = 81 relative to natural habitat and t = -2.95, p = 0.004, d.f. = 96 relative to low disturbance habitat), although no significant difference was found between the low disturbance and natural habitats (t = -0.18, p = 0.86, d.f. = 77) (Figure 3B). As for the distances between all burrows in the habitat, relative to the natural habitat, human activities led to the same decline in the inter-burrow distance in two disturbed habitats (Figure 2; Figure 3C). Besides, the FID of individuals in HDP derived from inter all burrow distance is shortest among all three habitats as expected (Figure 4A), nevertheless, though inter all burrow distances in LDP are the shortest among three habitats (Figure 4), and the home range size of pairs in LDH is significantly smaller than pairs in other two habitats (t = -3.34, p = 0.001, d.f. = 62 relative to HDH, and t = -4.02, p= 0.000, d.f. = 42 relative to NH) (Figure 4B), FID of individuals in the LDP are longer than marmots in HDP (t = 5.05, p = 0.000, d.f. = 46) and no differentiation emerged relative to individuals from NP (t = 1.36, p = 0.182, d.f. = 38) (Figure 4A).
Similarly, the characteristics of sites selected for the digging of reproductive burrows also differed depending on human activity levels. Relative to pairs in the low disturbance population, both reproductive pairs in the high disturbance population (χ2= 7.28, p = 0.007) and the natural population (χ2 = 5.89, p = 0.015) preferentially constructed their reproductive burrows on mounds raised above the level of the surrounding ground (Figure 5A). The volume of those mounds also differed between sites, with mounds used for reproductive burrows in the high disturbance population being significantly smaller than mounds in the natural habitat (t = -2.68, p = 0.014, d.f. = 19.7), and both of those habitats’ mounds being much smaller than the mounds selected by pairs in the low disturbance population (Figure 5B). Finally, the mean distance from reproductive burrows to the nearest road in the high disturbance habitat is significantly shorter than in the low disturbance habitat (t = -5.77, p = 0.000, d.f. = 15.97) (Figure 5C).