Causes of admission to a rehabilitation center for andean condors (vultur gryphus) in Chile

Abstract

Causes of admission to rehabilitation centers can provide valuable information about factors that cause mortality in the wild. We studied causes of admission to a rehabilitation center for 108 Andean Condors (Vultur gryphus) in Chile. Seventy-nine, 28, and one condor came from central, south, and northern Chile, respectively. From central Chile, an area with high human population, the majority of condors received were adults. The most frequent causes of admission to the rehabilitation center were poisoning (52%) and collisions with power lines (13%). Seventy-two percent of the radiographed birds showed ammunition in their bodies. Almost all the condors (85%) were received during the wintering period, when condors use the lowlands, thus increasing the probability of interaction with humans. The condors admitted from southern Chile, an area with low human pressure, were mainly juveniles. The most frequently admitted birds in the south were young birds that were trapped just after fledging (68%), which made up only 4% of the cases in central Chile. There were no poisonings or collisions with power lines. Only 25% of the radiographed birds were positive for ammunition. No seasonal variation in admissions was observed, indicating that risk factors in the southern zone did not operate on a seasonal basis. The sample of birds admitted from central Chile had similar sex and age structure as the wild population, with some bias toward juveniles, in contrast with the sample from southern Chile, in which young birds dominated. In conclusion, we observed an important anthropogenic effect on causal and temporal patterns of admissions to a rehabilitation center for Andean Condors; for the segment of the population in central Chile, the mortality pressure is apparently higher than expected under natural conditions, which could promote a demographic sink in this region.