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Vulpes velox Say (Swift Fox) habitat suitability study area for the central Northern Great Plains divided into northern and southern subecoregional subsections. Presence points used to inform the mixedeffects and individual subecoregional habitat suitability models are shown. Background data (shaded area) show the historical distribution of Swift Foxes (Sovada et al. 2009). Inset map shows the relationship of the study area to the full Northern Great Plains ecoregion. Hill, Blaine, and Phillips Counties, Montana, which emerged from the model as areas of high habitat suitability, are highlighted in both full and inset maps.
Source publication
Grassland-dependent Vulpes velox Say (Swift Foxes) occupy only a portion of their historical range in the North American Great Plains and remaining subpopulations are functionally disconnected due to habitat fragmentation and other barriers. Modeling habitat suitability is critical to identifying sites for habitat conservation and reintroduction an...
Contexts in source publication
Context 1
... the mixed-effects model showed that subecoregion did affect model performance, we built individual models to represent the northern and southern geographies (Fig. 1) ...
Context 2
... models included predicted habitat quality ranging from high to low. In the northern subecoregion, highest quality habitat was concentrated in Hill, Blaine, and Phillips counties of Montana ( Figs. 1 and 2). Lowest quality habitat was predicted on the western edge of the northern subecoregion where the terrain shifts to the foothills of the northern Rocky Mountains and surrounding areas of open water such as the Missouri River (Fig. 2). ...
Citations
... Grassland availability may be the most important factor to swift fox survival (Butler et al., 2021) and likely influential at dispersal-scale distances (x‾ = 15 km; Sovada et al., 2003). Swift fox primarily prey upon small mammals, insects, and birds (Kilgore, 1969) and construct burrows in suitable loamy soils (Weil and Brady, 2016) to avoid predation and raise kits (Harrison, 2003;Jackson and Choate, 2000;Kitchen et al., 1999;Olimb et al., 2021). The eastern edge of swift fox contemporary distributions, where landscape change is likely most prolific, has become a patchy matrix of grazed and un-grazed remnant native grasslands, intensive row-crop agriculture, and energy development (Drummond et al., 2012;Samson and Knopf, 1994;Sovada et al., 2009). ...
Grasslands are among the most widely distributed, but most imperiled, biomes on Earth. North American grasslands once covered ~162 million ha prior to European colonization, but only ~30 % of this landcover currently remains due to continued human-modified landscape changes. Strategic conservation of remaining grassland landcover, which considers species-specific habitat requirements, is critical for the persistence of grassland species and has become a global priority. Intact grassland landcover is critical for swift fox (Vulpes velox), a facultative prairie carnivore, and we sought to strategically identify areas where grassland conservation would most impact population persistence in an agro-prairie ecosystem. We modeled site (n = 381) occupancy by swift foxes using three years of camera-trap data (2018-2020) from western Kansas, USA, and integrated known-fate survival information to identify priority native grassland conservation areas. Additionally, we evaluated ownership of our identified priority conservation lands to determine strategies for conservation delivery. Our grassland assessment of two thresholds of predicted swift fox occupancy (≥0.09 [priority] and ≥0.18 [high priority]) identified 2,377,193 ha and 84,420 ha for conservation in Kansas, respectively. Identified conservation areas were overwhelmingly located on privately owned working lands (98 % [priority and high priority]), rather than federal, state, or non-governmental organization owned lands (2 % [priority and high priority]), and highlight the need for using conservation easements and incentive-based programs to promote grassland conservation to private landowners.
... Swift foxes (Vulpes velox) are small (~ 3 kg), prairie-obligate carnivores that occur at relatively low densities [range = 0.16-0.31 swift fox/km 2 (Schauster et al. 2002;Karki et al. 2007)] across their geographic range (Sovada et al. 2009;Schwalm et al. 2014;Butler et al. 2020;Olimb et al. 2021). Their prey includes small mammals, insects, and birds (Kilgore 1969) and they dig burrows in suitable soils for protection from predators and to raise kits (Kitchen et al. 1999;Jackson and Choate 2000;Harrison 2003;Olimb et al. 2021). ...
... swift fox/km 2 (Schauster et al. 2002;Karki et al. 2007)] across their geographic range (Sovada et al. 2009;Schwalm et al. 2014;Butler et al. 2020;Olimb et al. 2021). Their prey includes small mammals, insects, and birds (Kilgore 1969) and they dig burrows in suitable soils for protection from predators and to raise kits (Kitchen et al. 1999;Jackson and Choate 2000;Harrison 2003;Olimb et al. 2021). Swift fox populations were once extirpated across much of their range due to habitat loss and overkill [e.g., bounties, trapping, poisoning ( Fig. 1; Sovada et al. 2009)]. ...
... Loamy soil types are friable enough for digging and cohesive enough to not Desmond et al. 2000;Kretzer and Cully 2001] and may provide an indirect indication of prey availability. Soil textures (e.g., percentage of sand and clay), at a similar scale (1 ha), were important for determining habitat suitability for swift foxes in the Northern Great Plains (Olimb et al. 2021). Loamy soil types in our region occur in areas with gentle slopes (0-15%) and are generally greater in fertility, making these areas candidates for conversion to row-crop agriculture (EDIT 2021; Web Soil Survey 2021). ...
Context
Human-modified landscapes can structure species’ distributions and supplant traditional biotic range-limiting processes. Understanding the direction and scale of these processes is necessary to enhance species conservation efforts.
Objectives
We investigated how the distribution of a prairie-obligate carnivore, swift fox (Vulpes velox), is influenced by landscape pattern at the eastern edge of their used range. We also assessed the effects of a popular conservation effort, the conservation reserve program (CRP), on swift fox distributions.
Methods
We used three years of detection/non-detection data (2018–2020) from camera traps at 381 sites to evaluate the spatial distribution of swift foxes at the eastern edge of their extant range in Kansas, USA. We used Gaussian Kernel functions to identify optimal scales of effect for measured landscape covariates and multiseason use models to reveal potential range-limiting constraints.
Results
Swift foxes were more likely to occur at sites with moderate landcover diversity within 254.47 ha, greater proportion of shortgrass prairie (7.07 ha) and loamy soil types (0.79 ha), and lower proportions of CRP landcover (78.54 ha). Swift foxes were more likely to colonize sites with less diverse landcover, a greater proportion of loamy soil types, and lower proportions of CRP landcover. Swift foxes were insensitive to the proportion of row-crop agriculture surrounding sites (3.14 ha).
Conclusions
Loamy soils and distribution of shortgrass prairie ecosystems may shape the periphery of the distribution for swift foxes. Landscape-scale use of CRP may constrain swift fox distributions at their range edge because managed vegetation structure of CRP does not mimic native shortgrass prairie.
The Great Plains region has undergone extensive conversion of native prairies to agriculture production and energy development since European colonization. Temperate prairies, including remaining prairies within the Great Plains, are considered among Earth’s most imperiled ecosystems. Prairie patches now exist as components of a landscape mosaic proportionately dominated by cultivated agriculture. These contemporary human-modified landscapes may structure species’ distributions, influence community dynamics, and supplant established abiotic range-limiting processes. Understanding the direction and scale of these processes, and how they are affected by landscape composition and configuration, is necessary to enhance conservation efforts. Carnivore communities may be most affected by landscape changes due to negative interactions with humans and their inherent biological traits; however, information regarding landscape-scale effects on the existing suite of carnivores in the Great Plains is lacking. I examined how landscape composition and characteristics influenced site occupancy probabilities and turnover rates by swift foxes (Vulpes velox), the spatial and temporal interactions between swift foxes and coyotes (Canis latrans), and carnivore richness in agro-prairie ecosystems. Additionally, I strategically identified native prairie areas to focus conservation and management of remaining swift fox habitat.
During 2018-2020, I used detection/non-detection data from camera traps at 381 randomly selected sites distributed throughout a landscape mosaic comprising the westernmost 31 counties (7.16 million ha) of Kansas, USA. I subsequently used presence/absence data from these sites across three years to infer species-specific responses to landscape change and carnivore community dynamics. To evaluate effects of landscape composition and configuration on site occupancy probabilities and turnover rates by swift fox, I used a distance-weighted scale of effect of landscape metrics within multi-season occupancy models. Swift foxes were more likely to occur at sites with moderate landcover diversity within 254.47 ha, greater proportion of shortgrass prairie (7.07 ha) and loamy soil types (0.79 ha), and lower proportions of Conservation Reserve Program (CRP) landcover (78.54 ha). Swift foxes were more likely to colonize sites with less diverse landcover, a greater proportion of loamy soil types, and lower proportions of CRP landcover. Swift foxes were insensitive to the proportion of row-crop agriculture surrounding sites (3.14 ha). To evaluate landscape composition effects on swift foxes and coyote (the apex predator in the region) spatiotemporal interactions, I used a Bayesian hierarchical multi-season occupancy model to evaluate spatial interactions, and a coefficient of overlap of temporal activity to assess factors affecting temporal interactions. Mean persistence of swift foxes differed across sites where coyotes were not detected (0.66; SE = 0.001) and where coyotes were detected (0.39; SE=0.001). The coefficient of overlap at sites surrounded by lower proportions of CRP (≥0.10) differed (95% CIs did not overlap) from coefficient of overlap of all other landscape effects. The spatial distribution of swift foxes was positively influenced (Species Interaction Factor [SIF] > 1) by coyote presence through space and time at low proportions of CRP (≤0.04). SIF decreased as proportion of CRP increased; however, Bayesian confidence intervals overlapped SIF = 1, suggesting that swift foxes were spatially distributed independent of coyotes through space and time at greater proportions of CRP (>0.04).
I used a structural equation model to test hypotheses of multiple direct and indirect relationships between landscape composition and configuration and prey availability on carnivore richness. My hypothesized model (X2 = 23.92, df = 24, P = 0.47) explained 27% of the variance of carnivore richness. Agriculture, native prairie, landcover diversity, CRP, water availability, prey occurrence, and sampling effort all had direct positive effects on my measure of carnivore richness, while loamy tableland soil had only an indirect effect. To strategically identify native prairie areas for conservation of swift fox habitat, I created a predicted swift fox occupancy map based on my most-supported, stacked single-season occupancy model. I identified predicted occupancy rate (range = 0.01–0.46) where sensitivity equaled specificity (0.09) within a receiver operating characteristic curve, and reclassified the predicted occupancy map to include only predicted occupancy rates >0.09, and again for a more targeted approach with predicted occupancy rates >0.18. These two maps were intersected with a map of grassland proportions >0.60 to identify areas that were expected to have relatively high occupancy and survival rates by swift fox. Swift foxes were more likely to occur at sites with low levels of landscape diversity (β = -0.411 ± 0.140), greater proportions of native grassland (β = 0.375 ± 0.154) and loamy tableland soils (β = 0.944 ± 0.188), and lower proportions of CRP landcover (β = -1.081 ± 0.360). Identified native grassland conservation areas totaled 84,420.24 ha (mean patch size = 162.66 ha [SE = 29.67]). Conservation areas located on privately owned working lands included 82,703.86 ha, while conservation areas located within the boundaries of federal, state, and non-governmental organizations (NGO) parcels included 1,716.38 ha.
My results provide a unique understanding of how landscape composition and configuration, intraguild competition, and prey availability drive carnivore community dynamics in agro-prairie ecosystems. Additionally, my research elucidated constraints to range expansions for an iconic prairie-obligate carnivore (swift fox) at the edge of their range, while also identifying areas for strategic conservation for their populations.
