Advances in Reproductive Science for Wild Carnivore Conservation P Comizzoli 1 , AE Crosier 1 , N Songsasen 1 , M Szykman Gunther 1,2 , JG Howard 1 and DE Wildt 1 1 Department of Reproductive Sciences, Center for Species Survival, Smithsonian’s National Zoological Park, Washington, DC; 2 Department of Wildlife, Humboldt State University, Arcata, CA, USA Contents Knowledge about reproduction is critical for predicting the viability of wildlife populations in nature and for managing breeding programmes in captivity. Intensive species-based studies are the priority, because reproductive mechanisms are extraordinarily diverse, even within the same taxonomic family. Carnivores deserve more attention as such species are highly vulnerable to environmental change and human perse- cution. The present review provides contemporary illustrations of how reproductive science is contributing to understand unique reproductive mechanisms that are both of fundamental and applied interest. In the case of the endangered African wild dog (Lycaon pictus) free-living in South Africa, non- invasive faecal corticosteroid assessments have yielded new insights about the impact of animal relocation and reintroduction on adaptive responses, reproductive fitness and survival. For the maned wolf (Chrysocyon brachyurus), advances have been made in characterizing and comparing reproductive traits in free-ranging vs captive individuals. For the cheetah (Acinonyx jubatus), recent studies have focused on the cryosensitivity of sperm and the ability to develop a field- friendly sperm cryo-method. The by-product has been a large- scale frozen repository of sperm from wild-caught cheetahs useful for infusing new genes into ex situ populations. Finally, rigorous, multi-disciplinary and cross-institutional reproduc- tive studies of the black-footed ferret (Mustela nigripes), including the use of artificial insemination, have contributed to the remarkable recovery and restoration of this species, once on the brink of extinction. In summary, advances in repro- ductive science are not necessarily related to ‘assisted breed- ing’. However, understanding the unique ways of carnivore reproduction greatly contributes to species management and conservation. Introduction Reproduction is essential to the continuation and evo- lution of life. Therefore, this discipline naturally becomes a high priority investigative area in the general field of species conservation biology. There are two venues, the first being in situ (in natural habitats) and the second ex situ (in zoos). In both settings, the goal is to maintain sustainable populations, with zoos playing a stewardship role in creating reservoirs of wildlife that are as genet- ically close as possible to free-living counterparts. While the theory behind ensuring sustainable populations appears straightforward, the actual practice of studying and propagating endangered species is extraordinarily complex. Challenges include lack of specimens, danger- ous behaviours, stress susceptibility, need for genetic management and, most significantly, an enormous lack of scientific knowledge. For instance, reproductive mechanisms are well understood for only approximately 0.25% of the world’s 40 000 vertebrate species (Wildt et al. 2003). There are approximately 280 wild carnivore species, a rather charismatic group, albeit with an abysmal reproductive database and high susceptibility to environmental changes (i.e., habitat loss and frag- mentation, declining prey and disease transmission from domestic carnivores) and relentless human persecution (Wildt et al. 2001). For more than 3 decades, our laboratory has studied diverse felids, canids and muste- lids with one clear conclusion—there are as many mechanistic differences in carnivore reproduction as there are species (Wildt et al. 2001). As a result, the highest priority is for species-specific studies, to establish baseline data for animals that largely have been ignored. Beyond the scholarly benefits of such work, we have determined that resulting data have practical use in animal conservation efforts. This might include opti- mizing natural breeding to ensure genetic management in zoos or to implement intensive plans to recover an endangered species for reintroduction into native hab- itat. Additionally, characterizing biological norms has been useful to advance certain assisted reproductive technologies, including artificial insemination (AI), in vi- tro fertilization and embryo transfer. Unlike with livestock (or even purebred domestic dogs and cats), the goal of managing wildlife is to retain all existing gene diversity for at least the next century (Ballou 1997). This practice ensures species integrity, adaptiveness, resis- tance to disease and reproductive fitness. Assisted breeding, especially AI, has a significant role in ensuring genetic heterozygosity, especially when linked to the ability to move cryopreserved spermatozoa, thereby offering an approach to transfer genes between geo- graphically distant specimens or populations (Pukaz- henthi and Wildt 2004). Yet, other tools in reproductive science, especially the non-invasive monitoring of faecal hormonal metabolites (faeces or urine) have provided incredibly valuable information on reproductive status and function. In short, wild carnivores are benefiting from modern reproductive science in diverse ways. The objective of this review is to present contemporary examples that support this assertion; ranging from understanding the bio-complexities of species to advanc- ing assisted breeding to assist directly re-establishing endangered animals back into nature. Maintaining viable populations of African wild dogs in a fragmented landscape The African wild dog has been extirpated throughout much of its historical range, and <5000 free-living individuals now remain in southern Africa (Woodroffe et al. 2004). Interestingly, the endangered status of this species is not directly related to reproduction. Whether Reprod Dom Anim 44 (Suppl. 2), 47–52 (2009); doi: 10.1111/j.1439-0531.2009.01373.x ISSN 0936-6768 Ó 2009 No Claim to original US government works. Journal compilation Ó 2009 Blackwell Verlag GmbH