Home‐range size and spatial organization of black‐footed ferrets Mustela nigripes in South Dakota, USA

Abstract

Effective conservation planning for endangered species depends on an understanding of space use patterns. Blackfooted ferrets Mustela nigripes depend on prairie dogs Cynomys sp. as prey and use their burrow systems for shelter. The availability of areas with high densities of active prairie dog burrows is the major factor thought to affect their selection of sites and resources. However, we have little knowledge about how the spatial distribution of active prairie dog burrows might influence the spatial organization and home-range size of ferrets. We monitored the movements of black-footed ferrets on a black-tailed prairie dog C. ludovicianus colony in South Dakota to document ferret space use patterns. Home ranges of female ferrets were 22.9 -95.6 ha in size (x¼56.3 ha, SE¼19.7, N¼6), while male ferret home ranges were on average more than twice as large as those of females (x¼128.3 ha, SE¼68.5, N¼3). The home-range size of female ferrets was correlated with mean active prairie dog burrow utilization distribution (UD) value within ferret home ranges, where home-range size decreased as active prairie dog burrow UD value increased (r 2 ¼ 0.974, P , 0.001, N ¼ 6). Ferret space use overlapped more extensively than previously reported, with up to 43% UD overlap between a ferret and the nearest adjacent ferret of the same sex. Areas of overlap tended to have higher active prairie dog burrow UD values, suggesting that the spatial distribution of active prairie dog burrows influenced both home-range size and the amount of space use overlap between ferrets. These findings emphasize the potential influence of resource distribution on carnivore sociobiology and the importance of considering that distribution in assessing habitat for the reintroduction of specialized species.

Resource Selection Models are Useful in Predicting Fine-Scale Distributions of Black-Footed Ferrets in Prairie Dog Colonies

“…2), but not males. In addition, the negative correlation between sizes of UD ranges and densities of active burrow openings was significant for female ferrets in the study of Jachowski et al (2010). Therefore, these two studies collectively suggest that female ferrets tend to use smaller areas where active burrow openings are abundant, a trend that agrees with studies of other Mustela and the hypothesis that female Mustela are most concerned with acquisition of resources to support young, whereas males are more concerned with breeding (Erlinge and Sandell 1986, Sandell 1986, 1989.…”

“…Many studies suggest ferrets exhibit a developmentally fixed predisposition to defend space, perhaps regardless of habitat quality, which would limit the number of ferrets a habitat supports, thus supporting model 2 (Biggins et al 1985, Paunovich and Forrest 1987, Richardson et al 1987, Fagerstone and Biggins 2011, Livieri and Anderson 2012. However, in a recent study, Jachowski et al (2010) reported a few instances of intense same-sex space use overlap during June-October when adult female ferrets were rearing their young (i.e. kits).…”

“…Here, we discuss mean VI values because they provide a measure of central tendency. Restricting data from the Jachowski et al (2010) study to instances of same-sex overlap in area (using their Table 2 and Fig. 2), mean VI values from both studies were generally low (combined VI -0.16), suggesting much exclusive use of ranges by ferrets in both studies.…”

Use of Multi-Opening Burrow Systems by Black-Footed Ferrets

“…We present an examination of space use, resource selection, and territoriality by adult ferrets during the post-breeding season on a colony of blacktailed prairie dogs (hereafter prairie dogs, C. ludovicianus) in the Conata Basin, South Dakota, USA. The study colony was immediately adjacent to, and contained somewhat higher densities of burrow openings (144.7 ha 1 ) than the colony surveyed by Jachowski et al (2010: 129.3 ha 1 ). Overall, we hoped to increase understanding of the spatial ecology of M. nigripes and to evaluate the competing models for reserve design.…”

“…Prairie dog colonies differ in size, and contain varying densities of prairie dogs. In colonies with high densities of prairie dogs, ferrets can shrink their territories (Jachowski et al 2010) but it is unclear if ferrets tend to inhabit overlapping territories (model 1) or become crowded and compete for space (model 2). Many studies suggest ferrets exhibit a developmentally fixed predisposition to defend space, perhaps regardless of habitat quality, which would limit the number of ferrets a habitat supports, thus supporting model 2 (Biggins et al 1985, Paunovich and Forrest 1987, Richardson et al 1987, Fagerstone and Biggins 2011, Livieri and Anderson 2012.…”