By Griet Cuyckens, 30th November 2022
Mountains are important. They provide a considerable amount of the tangible and intangible resources used worldwide. In the eastern slopes of the Andes mountains, the forests, or Yungas, of north-west Argentina are no different. Anyone who has ever visited this region has likely been surprised not only by the beauty of the foggy mountain forests, but also by the widespread presence of cows—unfenced and roaming free in the forests, grazing and browsing on native herbs and trees, and trampling seedlings. But what impact do these cattle have on native mammals in one of the most biodiverse places in Argentina?
Working with camera traps has several limitations: they can be easily stolen by curious passers-by, stop working, be moved by the study object, or be too easily triggered and take thousands of pictures of moving grass. Plus, the steep slopes of the Austral Yungas, combined with extensive summer rainfall, complicate placing them. However, when things go to plan, seeing images of the wildlife is very rewarding.
By analysing our camera trap images, we discovered not only direct effects on native deer species and small mammals, but also indirect effects on six felid species. Cows directly affect small mammals by trampling vegetation and changing the forest understory, affecting the habitat available for wildlife, including rodents and the agouti and tapeti. Felids, however, appear to be able to coexist with cattle as they still have a sufficient prey base, but are threatened by other human activities such as selective logging and hunting. The most common felid species recorded on our camera traps was the ocelot.
The presence of people and their activities also had some impacts on large mammals of conservation concern, such as the lowland tapir, white-lipped peccary and jaguar. Few images of these species were captured by our camera traps, suggesting they may be rare in the Austral Yungas and that their long-term conservation is at risk. To aid the survival of jaguar populations in the region, we recommend the designation of large protected areas that manage hunting, protect livestock against predation and provide a network of corridors.
The steep relief of the Yungas makes the highest parts more difficult to access, thus less susceptible to human impacts, but those areas are also naturally poorer in native species and abundance. The Austral Yungas, in general, are less biodiverse than the Atlantic Forest in north-east of Argentina, but the seasonal climate, relief, and the presence of felid species that don’t occur in more tropical regions (such as the Pampas cat), make it unique.
Although, 65% of the Yungas is potentially suitable for cattle, lower production costs in lowland areas means production systems in mountain areas like the Austral Yungas are not competitive in the marketplace.
At present, several areas of this biodiverse ecoregion are burning and several of our study locations are currently threatened by fires, caused largely by negligence. Urgent action is needed to control these fires, which can be seen in real time here: firms.modaps.eosdis.nasa.gov/map/#d:2022-11-17..2022-11-18,2022-11-17;@-61.3,-23.0,7z.
Based on our analysis of both environmental variables (including altitude, latitude and climate) and human related variables (such as the human influence index and cattle habitat suitability), land protection is the key factor leading to higher native mammal diversity. We therefore recommend stricter controls over hunting and cattle exclusion in protected areas, as well as reduction of the presence of cattle in other land use types, such as private lands and areas with lower categories of protection.
The article “Effect of free-ranging cattle on mammalian diversity: an Austral Yungas case study” is available in Oryx—The International Journal of Conservation.