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Journal of Wildlife Diseases, 40(2), 2004, pp. 273–281 Wildlife Disease Association 2004

COMPARISON OF THREE FECAL STEROID METABOLITES FOR PREGNANCY DETECTION USED WITH SINGLE SAMPLING IN BIGHORN SHEEP (OVIS CANADENSIS)
Kathryn A. Schoenecker,1,3 Robin O. Lyda,2 and Jay Kirkpatrick2
United States Geological Survey-Biological Resources Discipline, Fort Collins Science Center, 2150 CentreAvenue, Building C, Fort Collins, Colorado 80526-8118, USA 2 Science and Conservation Center, 2100 S. Shiloh Road, Billings, Montana 59106, USA 3 Corresponding author (email: kate schoenecker@usgs.gov)
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ABSTRACT: We compared three fecal steroid metabolite assays for their usefulness in detecting pregnancy among free-ranging Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from BighornCanyon National Recreation Area, Wyoming and Montana (USA) and captive bighorn ewes at ZooMontana in Billings, Montana. Fecal samples were collected from 11 free-ranging, radio-collared bighorn ewes in late January–May 2001 and from 20 free-ranging, radio-collared ewes in late March to mid-May 2002. Free-ranging ewes were monitored the following spring to determine whether or not they lambed. Inaddition, two captive ewes were studied at ZooMontana. With three exceptions, free-ranging bighorn ewes that produced lambs had nonspecific progesterone metabolite (iPdG) levels of 1,800 ng/g feces and iPdG levels 7,000 ng/gm feces when samples were collected between early March and mid-May. Samples collected earlier in the year were inconclusive. One false negative was suspected to be the resultof sample collection error. Of the captive ewes, nonspecific pregnanediol-3 -glucuronide (PdG) and iPdG followed a predictable curve over the course of the 180-day pregnancies. We conclude that estrone conjugates are not useful in diagnosing pregnancy; however, fecal steroid analysis of PdG and iPdG can be used to accurately determine pregnancy and reproductive function in bighorn sheep. Thisholds great potential as a noninvasive technique for understanding the role of reproductive disease in wild bighorn sheep. Key words: Animal reproduction, bighorn sheep, fertility, noninvasive, Ovis canadensis canadensis, pregnancy.
INTRODUCTION

Developing noninvasive techniques for gathering biological information from wildlife is a goal of many wildlife managers and biologists. Handlingfree-ranging wild animals causes stress (DeForge, 1976), may disrupt reproductive events (Ballard and Tobey, 1981; Larsen and Gauthier, 1989), may confound endocrine status (Kirkpatrick et al., 1979), and can be stressful and dangerous to humans (Lasley and Kirkpatrick, 1991). Evaluations of sexual maturity, fertility, and reproductive status are useful and needed by managers to predict potentialsuccess of a population and for making general management decisions. Measures of reproductive success are also useful tools to help determine the health of a population (Lasley and Kirkpatrick, 1991). Monitoring reproductive function and reproductive success in freeranging wildlife by means of fecal and uri273

nary steroids has the potential to provide valuable information on the overall health ofthe population without the danger and stress of handling animals. Pregnancy detection by fecal steroid analysis has been successfully applied to a host of ungulate species including moose (Alces alces; Monfort et al., 1992; Schwartz et al., 1995), muskoxen (Ovibos moschatus; Desaulniers et al., 1989), bison (Bison bison; Kirkpatrick et al., 1992, 1993, 1996), Equus spp. (Bamberg et al., 1991;Kirkpatrick et al., 1991; Barkuff et al., 1993), caribou (Rangifer tarandus; Messier et al., 1990), and black rhinoceros (Diceros bicornis; Berkeley et al., 1997). Safar-Hermann et al. (1987) reported using nonspecific radioimmunoassay in four species (red buffalo [Syncerus caffer nanus], yak [Bos mutus], Grevy’s zebra [Equus grevyi], and Nubian ibex [Capra ibex nubiana]) successfully. Fecal steroid...
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