M. Ruiz Blanco
It is widely recognized that predatory interactions involving large carnivores play significant ecological roles on terrestrial communities. However, in the neotropics, these interactions have scarcely been studied. Particularly, there is a lack of information regarding ungulate neonatal predation and its consequence on prey population dynamics. Guanacos were the main puma prey in South America until they suffered a >90% population decline due to hunting and livestock ranching. Currently, intense predation in areas where pumas are supplemented by exotic prey could be preventing recovery of low-density guanaco populations, as newborns are particularly vulnerable to predation. This project aimed to (i) investigate guanaco mortality patterns during their first year of life, and (ii) evaluate potential effects of puma predation of juveniles on population dynamics. Researchers conducted a telemetry study in La Payunia Provincial Reserve, Mendoza, Argentina, which was created to protect one of the last and largest guanaco populations. The project complemented a previous survival study based on carcasses and radio telemetry of adults in the reserve since 2005.
Telemetry-based estimates were obtained of guanaco survival rates during the first year of life for the first time in Argentina and the second time in the entire species range; mortality causes and pattern were also studied. Twenty-eight newborn guanacos were successfully captured and radio ear-tagged during birthing season, with 61% surviving to first year. A critical period for newborn survival is during the first month of life, which is when most deaths occurred. Eighteen percent of the mortality events were caused by puma predation. A population dynamic model is being developed and simulation analyses are being conducted to evaluate the impacts of puma predation on guanaco population dynamics. The results will improve the ability to use a science-based approach for the conservation of guanaco populations and puma-guanaco interactions. Moreover, plans exist to radio ear-tag a new cohort of newborns next birthing season and monitor them during the year, providing more robust conclusions and the ability to begin exploring inter-year variation. ($7,900)