Determination, comparison and calibration of relative abundance indices and monitoring programs for the conservation of native carnivores Calden Forest, La Pampa, Argentina
J. Zanón Martínez
The Calden Forest region of central Argentina has been severely impacted by a variety of human activities. Native forests have been eliminated in favor of agricultural lands and the legal and illegal hunting of wildlife – predominantly carnivores – have presumably affected these species, but there have been no management or research efforts to determine the degree of impact. There is a rich carnivore community in the region, including the puma as apex predator, as well as three species of smaller felines: Geoffroy’s cat, Pampas cat and jaguarundi. In addition, the area is home to the Pampas fox, lesser grison (ferret family) and hog-nosed skunk.
This project developed, compared and calibrated abundance indices of the carnivore community, determining effective approaches for estimating population size that can be used to monitor populations in the Calden Forest and in other regions. In addition, they conducted a direct comparison of puma populations in a nature reserve (no legal hunting allowed) and a nearby game reserve (legal hunting promoted). The researchers attempted five different survey methods and quickly determined that two did not yield sufficient or suitable data to effectively monitor carnivore populations: following frequently-used animal trails and searching for identifiable tracks, which provided few tracks due to substrate quality; and, nocturnal eye-reflection surveys (detection of eye reflection of animals shined with a light at night), which yielded few sightings because of the vegetation structure of the area. Three techniques – tracks recorded along sand transects, tracks recorded at bait stations and camera-traps at bait stations – provided sufficient and high-quality data. Abundance estimates across all three methods correlated strongly with each other, suggesting that any of the methods were effective tools and that relative abundance estimates were likely to be correct. For pumas in particular, the camera-traps also allowed for individual identification, allowing for estimates of absolute abundance and a more in-depth comparison of abundance between the nature reserve and the game reserve.
Based on the different survey techniques, Zanón determined that the relative abundance of pumas in the nature reserve was 7 to 23 times higher than the game reserve. Using the camera-trap data from the nature reserve, he was able to individually identify 10 pumas, three males and seven females, four of which were accompanied by cubs. At the game reserve, only 2 pumas were identified, both females. These results were not surprising, given the nature reserve has abundant prey species for carnivores and the game reserve has witnessed intense hunting pressure on all game species (carnivores, prey species such as deer, etc). However, these methods allowed for the first quantitative relative and absolute abundance measures for these populations in the region, providing tested tools for monitoring wildlife in this and other areas. Zanón has presented his research to several wildlife management agencies and plans to work with them to improve conservation plans over the course of his graduate studies. ($9,500)