Research Article Fecal Hormones as a Non-Invasive Population Monitoring Method for Reindeer C-JAE C. MORDEN, 1 Department of Biology, Concordia University, 7141 Sherbrooke Street W., Montreal, QC, Canada H4B 1R6 ROBERT B. WELADJI, Department of Biology, Concordia University, 7141 Sherbrooke Street W., Montreal, QC, Canada H4B 1R6 ERIK ROPSTAD, Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway ELLEN DAHL, Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway ØYSTEIN HOLAND, Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432 A ˚ s, Norway GABRIELA MASTROMONACO, Reproductive Physiology, Toronto Zoo, 361A Old Finch Avenue, Scarborough, ON, Canada M1B 5K7 MAURI NIEMINEN, Finnish Game and Fisheries Research Institute, Reindeer Research Station, Fin-99910 Kaamanen, Finland ABSTRACT Proper management of threatened species requires knowledge of population sizes and struc- tures, however current techniques to gather this information are generally impractical and costly and can be stressful on the animals. Non-invasive methods that can produce high quality and accurate results are better alternatives. In winter 2010, we collected blood and fecal samples from 2 reindeer (Rangifer tarandus) populations (Kaamanen, Finland and Svalbard, Norway) to investigate the feasibility of using fecal proges- terone metabolites to help estimate the reproductive status, the sex, and the age structures of the populations. We first examined the relationship between plasma progesterone and fecal progesterone metabolite con- centrations. We further assessed whether fecal progesterone metabolite levels would clearly differ among calf, yearling, and adult and between pregnant and non-pregnant females. We quantified fecal progesterone metabolites (using enzyme immunoassay) and plasma progesterone (using radio immunoassay) of females and males of different ages from the 2 herds. We found in both populations that fecal progesterone metabolite levels reflected plasma progesterone concentrations. However, the range of fecal progesterone metabolite concentration was much wider in Finland than in Svalbard, possibly due to differences in diet or body condition. We determined a threshold value of 1.31 ng/ml plasma progesterone and 2025.93 ng/g dried fecal progesterone metabolites to identify pregnant reindeer from non-pregnant animals with 100% accuracy. We found a significant difference in fecal progesterone metabolite concentrations only between calves and yearlings/adults in Finland. We could not differentiate among males, non-pregnant adults, or calves of either sex; therefore identification of sex may have to rely on the use of DNA techniques. Our results suggest that hormone concentration, in combination with fecal DNA and pellet morphometry techniques, may provide important population parameters and is a valuable tool for the monitoring of reindeer and may have an application for threatened populations of woodland caribou throughout the winter and early spring. ß 2011 The Wildlife Society. KEY WORDS feces, non-invasive methods, pregnancy, progesterone metabolites, Rangifer tarandus, wildlife monitoring. Management and conservation of wild animals requires knowledge of demographic and population parameters, in- cluding sex ratio, age structure, and reproductive status of the individuals (Mysterud and Østbye 2006, Kuhl et al. 2009). Age structure varies within populations over time, and knowledge of these differences is critical for exploring trends in recruitment, population growth, survival, senescence, and reproductive status (Reilly 2002, Festa-Bianchet et al. 2003). Age-specific reproduction alone could aid our understanding of population performance and dynamics and could help predict future trends in population size (Gaillard et al. 2000, DelGiudice et al. 2007, Kuhl et al. 2009). Often, the techniques involved in gathering such information are stressful for the study animal (Co ˆte ´ et al. 1998, Cattet et al. 2008, Omsjoe et al. 2009) and can be extremely costly (Haigh 1979, Valkenburg et al. 1983). For example, current ungulate research involves a combination of the following methods: field observations by helicopter, physical control (capture via darting or net gunning), chemical immobilization, measure- ments of physical attributes, ear tagging, radiocollaring, and sample collections from the animal including blood, teeth, hair, and feces (DelGiudice et al. 2005). Therefore, techni- ques to gather accurate population parameters that can also avoid the harm and costs related to traditional sampling methods could be valuable. Blood is the traditional medium for examining hormones that can provide information on female reproductive status (via progesterone [P4] or estradiol; Ropstad et al. 2005, Received: 28 July 2010; Accepted: 1 February 2011; Published: 15 July 2011 1 E-mail: rweladji@alcor.concordia.ca The Journal of Wildlife Management 75(6):1426–1435; 2011; DOI: 10.1002/jwmg.185 1426 The Journal of Wildlife Management  75(6)