The Swift fox (Vupes velox) is a habitat specialist species of short or mixed grass prairie. We used bioclimatic envelope models and habitat suitability models under three future climate scenarios (based on CO2 emission rates) from &#x22;www.climatewizard.org&#x22;:http://www.climatewizard.org to fit species distribution models, using the maximum entropy method. Current suitable habitat for the swift fox covers an area of 161,984 km2. Under the future climate scenarios the habitat decreases by 27% in the low emission scenario, 63% for medium emissions, and 53% in the high emissions scenario. This decrease in suitable habitat corresponded to an overall decrease in total grassland landcover. The current total area of grassland is 423,440 km2. Under the future climate scenarios the grassland decreased by 12% in the low emissions scenario, 24% for medium emissions, and 16% in the high emissions scenario

Jennifer Redman

Kenneth  G. Boykin

Mark C. Andersen

Michael  T. Calkins

English

Michael Calkins

Mark Andersen

Kenneth Boykin

Crossref

Development of Future Habitat Suitability Models for the Swift fox (Vulpes velox) in the American Southwest

Nature Precedings

Jennifer M. Redman, Michael T. Calkins, Mark C. Andersen, and Kenneth G. Boykin
Center for Applied Spatial Ecology, New Mexico Cooperative Fish and Wildlife Research Unit, 
Department of Fish, Wildlife, and Conservation Ecology, 
New Mexico State University, Box 30003, MSC 4901, Las Cruces, New Mexico; redmanj@nmsu.edu
Development of Future Habitat Suitability Models for the Swift fox (Vulpes velox) in the American Southwest
Results
The majority of the suitable habitat for the Swift fox is located in eastern Colorado 
and New Mexico. The most suitable habitat was modeled under current conditions 
(161,984 km2). The high emissions scenario resulted in a 53% decrease in suitable 
habitat (75,520 km2), the medium emissions scenario resulted in a 63% decrease in 
suitable habitat (59,264 km2), and the low emissions scenario resulted in a 27% 
decrease in suitable habitat (118,032 km2).
The areas that were defined as suitable habitat types for the Swift fox were 
grassland herbaceous, montane mixed steppe shrubland, and grassland juniper 
woodland. These three landcover types was the only habitat area declared as 
suitable for the swift fox from both models. The total area of these three habitat 
types in the current scenario is 423,440 km2. The high emissions scenario resulted 
in a decrease of 16% (357,136 km2), medium emissions scenario resulted in a 
decrease of 24% (322,192 km2), and in the low emissions scenario resulted in a 
decrease of 12% (370,800 km2).
Suitable habitat for the Swift fox were a combined representation of bioclimatic 
envelope models as well as habitat suitability models. The AUC value (a measure 
of fit) for the bioclimatic envelope was 0.923 and for the habitat suitability model the 
AUC was 0.902. The bioclimatic envelope model on average predicted 10.5% more 
suitable habitat than the combined model across all four scenarios, while the habitat 
suitability model predicted an average of 5% more suitable habitat than the 
combined model . 
Abstract: The Swift fox (Vupes velox) is a habitat specialist species of short or mixed grass prairie. We used bioclimatic envelope models and habitat suitability models under three future climate scenarios (based on CO2 emission rates) from www.climatewizard.org to fit species 
distribution models, using the maximum entropy method. Current suitable habitat for the swift fox covers an area of 161,984 km2. Under the future climate scenarios the habitat decreases by 27% in the low emission scenario, 63% for medium emissions, and 53% in the high emissions scenario. This 
decrease in suitable habitat corresponded to an overall decrease in total grassland landcover. The current total area of grassland is 423,440 km2. Under the future climate scenarios the grassland decreased by 12% in the low emissions scenario, 24% for medium emissions, and 16% in the high 
emissions scenario. 
Discussion
Although much research has been done on the potential impacts of climate change 
on species at high latitudes and high elevations, much less is known about the 
effects on lower elevation temperate species. There was a dramatic decrease in 
suitable habitat for the grassland-specific Swift fox across all three future emission 
scenarios, including the one in which CO2 emissions drop below current levels. The 
greatest change in available total grassland occurred in the medium (current 
emissions) scenario with a 14% decrease, which led to a 63% decrease in potential 
suitable habitat for the Swift fox.
In addition, land-use change and habitat fragmentation or degradation were not 
considered in our models; thus, the actual suitable habitat can potentially be much 
less. The Swift fox is dependent upon short-grass prairies and the decrease of 
grasslands in the southwest will result in a further decrease of habitat and 
populations in the future. 
Literature Cited
Kam ler, J. F., Ballard, W . B., Fish, E. B., Lem ons, P. R., M ote, K., &  
Perchellet, C. C. 2003. Habitat
   use, hom e ranges, and survival of swift foxes in a fragm ented landscape: 
conservation 
   im plications. Journal of M am m alogy, 84, 989­995.
Cotterill, S. E. 1997. Status of the Swift Fox (Vulpes velox) in Alberta. Alberta 
Environm ental
    Protection, W ildlife M anagem ent Division, W ildilfe Status Report No.7, 
Edm onton, AB 17pp.
Methods
Two modeling techniques (habitat suitability and bioclimatic envelope) were used to 
predict the current and future suitable habitat for the swift fox. The climate data for the 
bioclimatic envelope model were obtained from www.climatewizard.org. The climate 
variables used were current and future annual and seasonal precipitation and average 
temperatures. The future climate scenarios were based on assumptions about emission 
rates in year 2050. In the Medium scenario the emission rate stays the same as at 
present, in the Low scenario, the emission rate declines, and in the High scenario, the 
emission rate increases. The variables used for the habitat suitability models were 
landcover, elevation, slope, and aspect. Future landcover was extrapolated from current 
landcover using the same current and future climate variables as the bioclimatic envelope 
models. These environmental layers were all gathered from the Southwest Regional GAP 
Project. All of the models were re-sampled to 4km resolution, and fitted using the 
statistical algorithm Maximum Entropy. There were 699 occurrence records used in the 
models; which were restricted to the 5 southwestern states (AZ, CO, NM, NV, UT) 
because the landcover data is incomplete for other states. These records were obtained 
from museum and natural history records and collections, and state agencies.  
The predictor variables that did not contribute to the current and future models were 
excluded and the models were refitted. The variables that contributed most to the Swift fox 
bioclimatic envelope models were Dec-Feb Precipitation, Jun-Aug Precipitation, Mar-May 
Average Temperature, and Mar-May Precipitation. The variables that contributed to the 
habitat suitability models were landcover, elevation, and slope. 
Each bioclimatic envelope model was combined with the corresponding habitat suitability 
model. These models were combined in order to reduce the over-prediction that occurs in 
both models; only the combined suitable areas of both models was declared as suitable 
habitat for the Swift fox.  
Legend
Swift fox (Vulpes velox)
Suitability
bioclimatic envelope 
model
habitat suitability model
non-suitable 
(both models)
suitable (both models)
Legend
Landcover
alpine shrubland
barren
deciduous forest
deciduous shrubland
desert mixed steppe shrubland
desert mixed succulent shrubland
desert shrubland
emergent herbaceous wetland
evergreen forest
evergreen shrubland
evergreen woodland
grassland herbaceous
grassland juniper woodland
mixed forest
montane mixed steppe shrubland
pinyon-juniper shrubland
pinyon-juniper woodland
woody wetland
Models  Suitable Habitat        Landcover Maps
Current Current
Low ScenarioLow Scenario
Medium Scenario Medium Scenario
High Scenario High Scenario
Introduction
Swift fox populations have been decreasing at least since the mid-1980s (Kamler, 2003). 
Habitat loss due to agriculture, competition with other canids, and predator control 
programs have  been implicated as causes of these declines in the past (Cotterill, 1997). 
However, climate change may have additional impacts on swift fox populations, through 
its effects on their habitat. This project was designed to model potential changes in the 
geographic distribution of the Swift fox due to the impacts of global climate change on 
habitat suitability and availability.  
Our approach was to compare and combine bioclimatic envelope models, which directly 
use climatic variables that are influential in determining the range of the species of 
interest, and gap-analysis habitat suitability models, which predict the species’ distribution 
on the basis of environmental variables such as vegetation/landcover type, elevation, 
slope, and aspect. Since both of these modeling approaches may lead to some over-
prediction, the two models were combined to produce a final model of future swift fox 
habitat.  
Acknowledgements 
This work was supported in part by grant num ber 52005881 to New M exico 
State University from  the Howard Hughes m edical Institute through the 
Undergraduate Science Education Program . Thanks to Dr. Jennifer Frey for 
her advice on this project. 
N
at
ur
e 
Pr
ec
ed
in
gs
 : 
do
i:1
0.
10
38
/n
pr
e.
20
09
.3
71
7.
1 
: P
os
te
d 
3 
Se
p 
20
09


http://precedings.nature.com/documents/3717/version/1

Development of Future Habitat Suitability Models for the Swift fox (Vulpes velox) in the American Southwest

Abstract

Similar works

Full text

Available Versions

Crossref

Nature Precedings