Field surveys can improve predictions of habitat suitability for reintroductions: a swift fox case study

Reintroductions are challenging, and success rates are low despite extensive planning and considerable investment of resources. Improving predictive models for reintroduction planning is critical for achieving successful outcomes. The IUCN Guidelines for Reintroductions and Other Conservation Translocations recommend that habitat suitability assessments account for abiotic and biotic factors specific to the species to be reintroduced and, where needed, include habitat quality variables. However, habitat assessments are often based on remotely-sensed or existing geographical data that do not always reliably represent habitat quality variables. We tested the contribution of ground-based habitat quality metrics to habitat suitability models using a case study of the swift fox Vulpes velox, a mesocarnivore species for which a reintroduction is planned. Field surveys for habitat quality included collection of data on the main threat to the swift fox (the coyote Canis latrans), and for swift fox prey species. Our findings demonstrated that the inclusion of habitat quality variables derived from field surveys yielded better fitted models and a 16% increase in estimates of suitable habitat. Models including field survey data and models based only on interpolated geographical and remotely-sensed data had little overlap (38%), demonstrating the significant impact that different models can have in determining appropriate locations for a reintroduction. We advocate that ground-based habitat metrics be included in habitat suitability assessments for reintroductions of mesocarnivores.

Home range size and resource use by swift foxes in northeastern Montana

Swift foxes (Vulpes velox) are endemic to the Great Plains of North America, but were extirpated from the northern portion of their range by the mid-1900s. Despite several reintroductions to the Northern Great Plains, there remains a ~350 km range gap between the swift fox population along the Montana and Canada border and that in northeastern Wyoming and northwestern South Dakota. A better understanding of what resources swift foxes use along the Montana and Canada border region will assist managers to facilitate connectivity among populations. From 2016 to 2018, we estimated the home range size and evaluated resource use within the home ranges of 22 swift foxes equipped with Global Positioning System tracking collars in northeastern Montana. Swift fox home ranges in our study were some of the largest ever recorded, averaging (± SE) 42.0 km2 ± 4.7. Our results indicate that both environmental and anthropogenic factors influenced resource use. At the population level, resource use increased by 3.3% for every 5.0% increase in percent grasslands. Relative probability of use decreased by 7.9% and 7.4% for every kilometer away from unpaved roads and gas well sites, respectively, and decreased by 3.0% and 11.3% for every one-unit increase in topographic roughness and every 0.05 increase in normalized difference vegetation index (NDVI), respectively. Our study suggests that, to reestablish connectivity among swift fox populations in Montana, managers should aim to maintain large corridors of contiguous grasslands at a landscape scale, a process that likely will require having to work with multiple property owners.

Winter movement behavior by swift foxes (Vulpes velox) at the northern edge of their range

Winter can be a limiting time of year for many temperate species, who must access depressed prey resources to meet energetic demands. The swift fox (Vulpes velox (Say, 1823)) was extirpated from Canada and Montana (USA) by 1969, but was reintroduced in the 1980s to Canada, and subsequently spread into northern Montana. Swift foxes in this region are at the current northern range edge where winter conditions are harsher and persist longer than in their southern range (i.e., Colorado (USA) to Texas (USA)). We collected fine-scale locational data from swift foxes fitted with global positioning system collars to examine movement and resource-use patterns during winter of 2016–2017 in northeastern Montana. Our results suggest that swift foxes displayed three distinct movement patterns (i.e., resting, foraging, and travelling) during the winter. Distance to road decreased relative probability of use by 39%–46% per kilometre across all movement states and individuals, whereas the influence of topographic roughness and distance to crop field varied among movement states and individuals. Overall, while our findings are based on data from three individuals, our study suggests that across movement states during the critical winter season, swift foxes are likely using topography and areas near roads to increase their ability to detect predators.

Using constructed covers to protect infrared cameras while surveying wildlife along roadways

We examined the effectiveness of simulated underground utility cable markers in hiding infrared cameras along a roadway. Our study took place in the summer of 2014 and winter of 2015 as part of a survey to determine whether swift fox (Vulpes velox) were present along the route of a planned highway expansion project in western Nebraska. Camera covers were constructed of square vinyl posts modified to conceal and camouflage the camera, and used in conjunction with a scent attractant. Camera stations were placed approximately 1.6 km apart and ran for 5 nights along a 200 km stretch of the planned construction site. There were 2,135 trap nights in the study. No camouflaged cameras were taken or disturbed in any way. The only camera placed along the roadway during the survey that was not placed in one of our covers was cable-locked to a utility pole. It was stolen within 3 days. By allowing cameras to remain in the right-of-way (ROW), obtaining access to place the cameras was greatly facilitated in many areas. The cost per camera cover was approximately $20. We conclude this method of disguising cameras is an effective one for roadside use.

Using constructed covers to protect infrared cameras while surveying wildlife along roadways

We examined the effectiveness of simulated underground utility cable markers in hiding infrared cameras along a roadway. Our study took place in the summer of 2014 and winter of 2015 as part of a survey to determine whether swift fox (Vulpes velox) were present along the route of a planned highway expansion project in western Nebraska. Camera covers were constructed of square vinyl posts modified to conceal and camouflage the camera, and used in conjunction with a scent attractant. Camera stations were placed approximately 1.6 km apart and ran for 5 nights along a 200 km stretch of the planned construction site. There were 2,135 trap nights in the study. No camouflaged cameras were taken or disturbed in any way. The only camera placed along the roadway during the survey that was not placed in one of our covers was cable-locked to a utility pole. It was stolen within 3 days. By allowing cameras to remain in the right-of-way (ROW), obtaining access to place the cameras was greatly facilitated in many areas. The cost per camera cover was approximately $20. We conclude this method of disguising cameras is an effective one for roadside use.