Document Type

Thesis - Open Access

Award Date

2011

Degree Name

Doctor of Philosophy (PhD)

Department / School

Natural Resource Management

First Advisor

Jonathan A. Jenks

Keywords

badlands national park, south dakota, swift fox, population

Abstract

The swift fox (Vulpes velox) was historically distributed in southwestern South Dakota including the region surrounding Badlands National Park (BNP). The species declined during the mid-1900s due to habitat fragmentation, non-target poisoning, and harvest. A remnant population occurred on USDA Forest Service lands in Fall River County, South Dakota. Following the successful reintroduction of the species in Canada (1983), a reintroduction program was initiated in BNP in the year 2003. Free-ranging swift fox from Colorado and Wyoming were translocated to BNP from 2003 to 2006. Despite these releases and observations of free-ranging swift fox occurring throughout western South Dakota, it was not known if a viable population occurred in western South Dakota. My study objectives were: (1) To determine the age-specific survival of the reintroduced swift fox population at BNP and surrounding area, (2) to determine the genetic diversity of the reintroduced population at BNP and (3) to determine habitat selection of female swift fox during the pup-rearing period (May – July), and finally, (4) to determine the viability of the reintroduced swift fox population at BNP and surrounding area. Monthly apparent survival probability of pups, yearlings, and adults was 0.88 (95% CI: 0.86-0.90), 0.90 (95% CI: 0.88-0.92), and 0.93 (95% CI: 0.91-0.94), respectively, in our study area. Accordingly, the annual apparent survival probability of pups, yearlings, and adults in our study area was 0.22, 0.29, and 0.39, respectively. We measured genetic diversity of the reintroduced swift fox population at BNP and surrounding area, and in an area of Colorado and Wyoming from where swift foxes were translocated to BNP, as well as the local swift fox population neighbouring BNP in Fall River County, South Dakota, using 12 microsatellite loci in Program Fstat version 2.9.3. We obtained mean gene diversity values of 0.778 (SD=0.156) for the Colorado population, 0.753 (SD=0.165) for the Wyoming population, 0.751 (SD=0.171) for the BNP population, and 0.730 (SD=0.166) for the Fall River population. We obtained an Fst value of 0.029 for the BNP and Fall River fox population, and an Fst value of 0.014 for the Colorado and Wyoming fox populations. We also obtained an Fst value of 0.020 for the Colorado and Fall River populations as well as an Fst value of 0.0246 for the Wyoming and Fall River populations. Analyses of location data from 13 radiomarked lactating female foxes indicated disproportional use (P < 0.001) of some habitats relative to their availability within swift fox home ranges. Swift foxes used grassland (ŵ = 1.01), sparse vegetation (ŵ = 1.4) and prairie dog towns (ŵ = 1.18) in proportion to their availability, whereas they were less likely to use woodland (ŵ = 0.00), shrubland (ŵ=0.14), pasture/agricultural-land (ŵ = 0.25) and development (ŵ = 0.16) relative to availability. Swift foxes typically are located in habitats that provide greater visibility, such as shortgrass prairie and areas with sparse vegetation; which allow detection of approaching coyotes (Canis latrans: primary predator of swift foxes). We used Progam VORTEX 9.99b to assess the viability of the reintroduced swift fox population at BNP and surrounding area incorporating data on the pedigree of the initial population. According to our findings, the reintroduced swift fox population at BNP had a 100% chance of extinction in the next 10 years with a negative growth rate under current conditions. The sensitivity analysis showed mortality rate to be the major cause of probability of extinction. Even a slight increase in survival (33% for pups and 45% for adults) would be capable of maintaining a stable population with a positive growth rate. The probability of population extinction, mean population size, and genetic diversity are crude estimations obtained from data on diverse interacting processes that are too complex to be integrated intuitively. Thus, the outcomes of this PVA should be considered an attempt to identify the factors affecting the persistence of the reintroduced population rather than using it to estimate accurate extinction probabilities and genetic changes to the population. To ensure viability of the reintroduced population, the survival rate of the foxes should be increased by increasing availability of suitable habitat, increasing prey availability, and keeping predators under control. Moreover, the population should be monitored periodically to assess demographic rates and genetic diversity.

Library of Congress Subject Headings

Kit fox -- Population viability analysis -- South Dakota -- Badlands National Park
Kit fox -- Reintroduction -- South Dakota -- Badlands National Park

Format

application/pdf

Number of Pages

115

Publisher

South Dakota State University

Rights

Copyright © 2011 Indrani Sasmal. All rights reserved.

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