Date Published: June 5, 2008
Publisher: BioMed Central
Author(s): Rodolfo Ungerfeld, Solana González-Pensado, Alejandro Bielli, Matías Villagrán, Daniel Olazabal, William Pérez.
The pampas deer (Ozotoceros bezoarticus) is a South American grazing deer which is in extreme danger of extinction. Very little is known about the biology of the pampas deer. Moreover, most information has not been published in peer-reviewed scientific journals, and is only available in local publications, theses, etc. Therefore, our aim was to update and summarize the available information regarding the reproductive biology of the pampas deer. Moreover, in most sections, we have also included new, unpublished information. Detailed descriptions are provided of the anatomy of both the female and the male reproductive tract, puberty onset, the oestrous cycle and gestational length. Birthing and the early postpartum period are described, as are maternal behaviour and early fawn development, seasonal distribution of births, seasonal changes in male reproduction and antler cycle, reproductive behaviour, semen collection, and cryopreservation. Finally, an overview is given and future directions of research are proposed.
The pampas deer, Ozotoceros bezoarticus (Linnaeus, 1758), used to be a widespread species originally distributed in the open grasslands (pampas and savannas) in eastern South America, from 5° to 41° S . In the 1800s naturalists and voyagers reported great abundance of this species [1-3]. It was the most widespread cervid in Uruguay . Reports of explorers and pioneer settlers as well as the folklore clearly tell how the pampas deer could be found in larger groups throughout the grasslands during the 17th and 18th centuries. Even place names in the region bear witness to the widespread distribution of this species. Some records report that more than 2,300,000 deer skins were exported during the 19th century from the Río de la Plata . However, due to man’s direct and indirect influence the population has decreased substantially in both size and distribution. This decrement has been explained by habitat fragmentation, agricultural development and competition with farmed animals , unregulated hunting  and transmission of infectious diseases .
Until recently, only three subspecies of the pampas deer were recognized: O. bezoarticus bezoarticus, occurring in Brazil, O. bezoarticus celer, in Argentina, and O. bezoarticus leucogaster, in southwestern Brazil, northeastern Argentina (Corrientes) and southeastern Bolivia . Cabrera  and Jackson  were unable to describe the taxonomic characteristics of the Uruguayan populations. The existence of two different subspecies endemic in Uruguay, O. bezoarticus arerunguaensis (Salto, northwestern Uruguay) and O. bezoarticus uruguayensis (Sierra de Ajos, Rocha, southeastern Uruguay), was described based on cytogenetics and molecular  and morphometric  data.
The pampas deer has received less attention that it should, considering the limited distribution of the species. In particular, important aspects of the reproduction of this species are unknown. In this review we have summarized mainly anatomical and behavioural information on the species. Some of this information has already been published and studied systematically while some is preliminary evidence or describes single observations that require more research. However, one aspect that is mostly unexplored is the physiology of reproduction in pampas deer. Our research group aims to investigate all aspects of pampas deer reproduction so that this knowledge and the available modern reproductive techniques can be used to improve the situation of the species. Management and the use of appropriate techniques have been shown to be effective in improving reproductive rate in other ruminants. In this case, a strategy of conservation of pampas deer should include this type of intervention. Therefore, there is significant need to continue doing research in this species. Basic information such as the age at which pampas deer reach puberty, first oestrous cycle, and the gestational length have not been systematically determined. The availability of this type of information is critical to enable us to manage and intervene to improve reproductive rates in captive animals and the condition of the species for conservation in wild populations.
CITES: Convention on International Trade in Endangered Species of Wild Fauna and Flora. ECFA: Estación de Cría de Fauna Autóctona; Native Fauna Breeding Station. UICN: International Union for Conservation of Nature and Natural Resources.
The authors declare that they have no competing interests.
RU began and coordinated the research performed at the ECFA, was SG-P’s and MV’s advisor, drafted the manuscript, and co-ordinated the writing and editing of the ms. SG-P wrote the courtship and mating behaviour sections, helped directly in writing the sections on agonistic behaviour, marking, and birthing and the early postpartum period, as well as the maternal behaviour and early fawn development sections. SG-P also collected important unpublished data included in the manuscript. AB wrote the sections dealing with seasonal reproductive patterns and reproductive technologies, i.e. semen collection and cryopreservation. AB also reviewed and helped with most sections, and collected unpublished data. MV wrote the section on male agonistic behaviour, and the chemical communication and male reproduction sections, and helped writing the courtship and mating behaviour, birth and early postpartum, and maternal behaviour and early fawn development sections, as well as collecting important unpublished data included in the manuscript. DO wrote the basic text on birthing and the early postpartum period, and on maternal behaviour and early fawn development. DO also helped to draft, and reviewed, the manuscript. WP collected the original data related to anatomical sections, and helped with the editing of the manuscript.