Tools and Technology Article Validation of Fecal Glucocorticoid Metabolite Assays for South African Herbivores SATHYA K. CHINNADURAI, 1 Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Natural Resources Building, Columbia, MO 65211, USA JOSHUA J. MILLSPAUGH, 2 Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Natural Resources Building, Columbia, MO 65211, USA WAYNE S. MATTHEWS, Ezemvelo KwaZulu-Natal Wildlife, Tembe Elephant Park, Private Bag X356, KwaNgwanase 3973, South Africa KIRSTEN CANTER, School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban 4041, South Africa ROB SLOTOW, School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban 4041, South Africa BRIAN E. WASHBURN, United States Department of Agriculture, Wildlife Services, National Wildlife Research Center, 6100 Columbus Avenue, Sandusky, OH 44870, USA RAMI J. WOODS, Department of Fisheries and Wildlife Sciences, University of Missouri, 302 Natural Resources Building, Columbia, MO 65211, USA ABSTRACT Fecal glucocorticoid metabolite (FGM) assays are a popular means of monitoring adrenocortical activity (i.e., physiological stress response) in wildlife. Species-specific differences in glucocorticoid metabolism and excretion require assay validation, including both laboratory and biological components, before assay use in new species. We validated a commercially available radioimmunoassay (MP 125 I corticosterone RIA kit [MP Biomedicals, Solon, OH]) for measuring FGMs of several South African herbivores, including giraffe (Giraffa camelopardalis), impala (Aepyceros melampus), nyala (Tragelaphus buxtoni), kudu (Tragelaphus strepsiceros), wildebeest (Connochaetes taurinus), and zebra (Equus burchelli). These herbivores are important in South African parks and reserves for ecotourism and as a prey base for predators and serve an integral role in ecosystem processes. Standard biochemical validations (e.g., recovery of exogenous corticosterone, intra- and interassay variation, and parallelism) demonstrated that the assay accurately and precisely measured FGMs of all 6 herbivore species. Our biological validations demonstrated that the assay was sensitive enough to detect changes in FGM production associated with season. Samples collected during the dry season (Jun–Aug) contained higher FGM concentrations than those from the wet season (Dec–Feb) in all species. We established optimal sample dilutions and reference FGM levels for these 6 herbivores, which can now be used to monitor the effects of management and ecotourism activities on the stress responses of these herbivores. (JOURNAL OF WILDLIFE MANAGEMENT 73(6):1014–1020; 2009) DOI: 10.2193/2008-430 KEY WORDS adrenal activity, assay validation, fecal glucocorticoid assay, herbivore, physiological stress, radioimmunoassay, stress, South Africa. In South African parks, officials make management decisions about wildlife based on the needs of local communities, interests of the park visitors, and many ecological considerations, including carrying capacity of the area. Managers attend to the interests of tourists by providing roads, lodging, and vehicles in natural habitat and by promoting accessibility for animal viewing. Increased vehicle and human activity can elicit a physiological stress response in wildlife (Wasser et al. 1997, Creel et al. 2002, Tempel and Gutie ´rrez 2004, Thiel et al. 2008), causing them to deviate from normal habitats, diets, and behaviors. Although response to an acute stressor can be adaptive in the short-term by redirecting resources to mobilize energy used, if conditions persist and the physiological stress response becomes chronic, the events can lead to decreased immune function, reduced reproductive capacity, and diminished survival (Sapolsky et al. 2000, Pride 2005). If ecotourism and wildlife health are incompatible, then wildlife conservation will suffer. The key to successful management of physiological stress in wildlife is accurate detection and monitoring of stress hormones (i.e., gluco- corticoids). Animals respond to external stimuli through multiple mechanisms and stress hormones are commonly used to measure adrenocortical activity. Stress hormones can be detected in blood, tissues, urine, and feces (Harvey et al. 1984, Wingfield et al. 1994, Wasser et al. 2000). However, with free-ranging animals the response to capture, handling, and blood collection might induce a physiological stress response and complicate data interpretation (Le Maho et al. 1992, Cook et al. 2000). Procedures have been developed to quantify adrenal activity noninvasively, through measure- ment of fecal glucocorticoid metabolite (FGM) levels (Graham and Brown 1996, Wasser et al. 2000, Millspaugh et al. 2002, Keay et al. 2006, Rothschild et al. 2008). In many studies investigating effects of multiple stressors, fecal studies have the added benefit of showing cumulative effects of stressors because they contain metabolites of stress hormones produced over a period, whereas plasma samples provide only hormone levels at one point in time (Harper and Austad 2000, Wasser et al. 2000, Millspaugh and Washburn 2004). After extensive hepatic and gastrointes- tinal metabolism (Bokkenheuser and Winter 1980, Schwar- zenberger et al. 1991), there is little parent hormone remaining in fecal material and a variety of glucocorticoid 1 Present address: Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606, USA 2 E-mail: MillspaughJ@missouri.edu 1014 The Journal of Wildlife Management N 73(6)