Speed of extirpation of the huemul in the history of human occupation in Patagonia

ZULIANI, MELINA E.; SMITH-FLUECK, JO ANNE M.; FLUECK, WERNER T.; MONJEAU, ADRIAN J.

Animal Production Science

CSIRO

Año: 2023

1836-0939

The Patagonian huemul, an endangered Odocoilinedeer, has an estimated 350–500individuals remaining in Argentina. Today’s population size, representing a numerical reductionof >99% of original estimates, is fragmented into small groups along ~2000 km of Andeanmountains. The species’ numbers were heavily reduced by past overexploitation and theydisappeared in areas of high anthropogenic activity, predominantly the fertile valley bottoms.Aims. This research delineates the current potential distribution of Patagonian huemul by usingclimatic indicators, topographic and vegetational proxies, and anthropogenic pressure, todetermine the relevance of the climatic envelope on current distribution. Methods. Occurrencerecords (latitude and longitude) were compiled (n = 159) by consulting the literature. Twentyenvironmental variables were used (WorldClim database) and two other representative environmental variables (normalised difference vegetation index (NDVI) and enhanced vegetation index(EVI)) were added to test their predictive power. We added the human footprint index (HFP) asa variable to control for model bias. Using the maximum entropy algorithm (MaxEnt), wemodelled the species’ potential distribution. We designated the historical distribution as areaM. Additionally, we calculated three areas of distribution: current, historical and potential. Finally,we calculated distributional retraction of the species and area lost per year. Key results. Themodel showed good predictive power (AUCTest = 0.764 ± 0.091). However, low values wereobtained for AUCtrain and AUCprom for the different predictor scenarios. Although the modelshows the interaction among several climatic, environmental, and topographic variables, thehuman footprint index (39.9%) was the variable that most influenced the current potentialdistribution of this species. Conclusion. Our model shows that most of Patagonia’s surface isclimatically suitable for huemul. This suggests that the causes of distributional retraction arenot related to limitations imposed by the climate envelope, but rather concur with recentresearch showing impact owing to the species’ behavioural response to anthropogenic activity.Implications. Current populations are small, fragmented, and confined to poor-quality sites.Although the species is currently found mainly within protected areas, management actions mustbe initiated that promote innovative strategies in unprotected areas, as well as high-valuehabitats, particularly as protected areas contain limited fertile lower-valley habitats