Habitat loss is one of the main threats to wildlife, particularly large mammals. Estimating the potential distribution of threatened species to guide surveys and conservation is crucial, primarily because such species tend to exist in small fragmented populations. The Endangered huemul deer Hippocamelus bisulcus is endemic to the southern Andes of Chile and Argentina. Although the species occurs in the Valdivian Ecoregion, a hotspot for biodiversity, we have no information on its occupancy and potential distribution in this region. We built and compared species distribution models for huemul using the maximum entropy approach, using 258 presence records and sets of bioclimatic and geographical variables as predictors, with the objective of assessing the potential distribution of the species in the Valdivian Ecoregion. Annual temperature range and summer precipitation were the predictive variables with the greatest influence in the best-fitting model. Approximately 12,360 km2 of the study area was identified as suitable habitat for the huemul, of which 30% is included in the national protected area systems of Chile and Argentina. The map of potential distribution produced by our model will facilitate prioritization of future survey efforts in other remote and unexplored areas in which huemul have not been recorded since the 1980s but where there is a high probability of their occurrence.

Conservation interventions increasingly involve active management of relative species abundances, especially when taxa of conservation concern are threatened by complex food web interactions. Unfortunately, the complexity of such interspecific interactions means that well-meaning management interventions can have unexpected, sometimes detrimental, effects on the species they are intended to protect. Here we report that the abrupt removal of an abundant non-native prey species (domestic sheep) and the cessation of predator control, actions intended to protect huemul deer Hippocamelus bisulcus in the future Patagonia National Park, appear to have had negative effects on this Endangered ungulate. During and following the changes in predator–prey management, predation of huemul fawns and females older than 1 year by native culpeo foxes Lycalopex culpaeus and pumas Puma concolor increased 3- and 5-fold, respectively. Predictions from demographic models suggest that elevated mortality rates of female huemul older than 1 year will, on average, cause this population of huemul to decline. These results highlight risks of unintended consequences when aggressive management actions are taken to protect taxa embedded in complex food webs. They also suggest that careful consideration of both inter- and intra-trophic level effects among all species in a system is warranted before conservation interventions are undertaken.

The conservation of threatened species poses many challenges but through cooperation and pooling of resources, individuals and organizations can work together to achieve better results. Here we describe our experience, working through a governmental and private alliance, studying one of the most threatened mammals in the Southern Cone. The huemul deer Hippocamelus bisulcus, one of two members of the Hippocamelus genus of South America, is endemic to Argentina and Chile and currently inhabits only a small fraction of its former range. Little is known about the huemul because it generally lives in remote areas with a harsh climate and rugged terrain. Using drive counts and fixed width transects over 5 consecutive years (2004–2008) we estimated density and abundance, and examined population changes and social structure, in three coastal huemul populations in the area of the Témpanos and Bernardo fjords of Bernardo O'Higgins National Park, Chile. Our results suggest that synergistic conservation actions, such as cattle removal and poaching control, can lead to the recovery of threatened huemul. The baseline information obtained from our surveys and the lessons learned through this governmental and private alliance will be useful for future monitoring of the huemul in the Patagonian fjords of Chile.

Considerable efforts have been invested in recent years to improve methods for both data collection and analyses required for population monitoring. Where historical or current estimates of population size are not adjusted for detection probabilities they may be too inaccurate to provide meaningful estimates of trends and thus monitoring methods need to be adapted. Here, we use data from the Endangered huemul deer Hippocamelus bisulcus to outline a framework to develop accurate robust estimates of detection probabilities that can be incorporated into new surveys in a cost-effective way and applied to existing survey data sets. In particular, by retroactively estimating detection probabilities for surveys of huemul, we show that current survey methods for huemul are inadequate to determine population trends reliably. Based on these results we propose a new monitoring method for the huemul and discuss the importance of estimating accuracies of historical survey data to ensure that changes in the abundance of the species reflect real population trends and are not an artefact of variation over time in the accuracy of survey data.