Ecología Austral (Jun 2005)
A preliminary analysis of death cause, capture-related mortality, and survival of adult red deer in northwestern Patagonia
Abstract
The red deer (Cervus elaphus), among the world’s 14 most invasive exotic mammals, has recently arrived in Patagonia. Forty-seven deer were captured, marked with radio collars, and monitored in order to determine survival rates and identify causes of death. Net gunning from a helicopter allowed captures to be evenly distributed through the study area and in a timely manner. The absence of capture related mortality in our study agrees with previously reported low rates for this method. Animals were monitored for periods ranging from 5 to 2611 days. Ten animals provided censored values due to radio failures or being shot: they survived on average 811 days (SE = 221) after capture. Ten animals experienced natural deaths with an average time alive after capture of 413 days (SE = 106): eight were killed by puma (Puma concolor). The remaining 27 animals were alive for an average of 974 days (SE = 52). Twenty-one percent of the animals died naturally during 38.549 deer-days. Using the Kaplan-Meier procedure, the annual survival rates for the years 2001-2003 were 0.89, 0.91 and 0.92 respectively (n = 47); the average annual survival rate being 91%. Although predation was the most important cause of adult mortality, all mortality sources combined (puma predation, legal and illegal hunting, disease, emigration) have not maintained deer population density low enough to prevent food limitation from occurring in the recent past.
