Mammals In The Sibinacocha Watershed
The high-elevation grasslands of the Andean Altiplano are among the least-studied biological ecosystems in the world. Low oxygen levels, rugged terrain, and extreme temperature shifts create one of the most extreme environments on Earth. Life in this region has had to adapt to these harsh conditions resulting high levels of endemism (species that are found nowhere else). Species that live in this extreme ecosystem tend to be found in small, isolated populations leaving them vulnerable to growing pressure from increased human activity and rapid climate change. Conservation plans are needed to protect these populations from growing threats, however, very little is known about even the most basic natural history, ecology, and distribution of many of these species, making conservation efforts extremely difficult. The Lake Sibinacocha watershed and the surrounding mountains in the Cordillera Vilcanota provide a unique opportunity to study the mammalian community of this fragile environment.
In the alpine regions of the Cordillera Vilcanota, there are two groups of mammals: 1) larger carnivores and ungulates that are able to move long distances to seek out adequate habitat and resources, and; 2) smaller rodents that are restricted to isolated talus slopes due to a limited ability to disperse and to overgrazing by domestic livestock. These two groups are intimately linked. Rodents provide the prey base for smaller carnivores and are also important seed dispersers and therefore impact available food for other herbivores. As such, knowledge about what rodent species are present in the region, as well as their distribution and ecology, is an essential component to learning where and how the larger members of the mammalian community will be found. A dramatic example of this linkage can be seen with the Andean Mountain cat (Leopardus jacobita), one of the most endangered cats in the world. Although this small cat may always have been rare, its current scarceness may be a direct result of the decline of one of its main prey species, the short-tailed chinchilla (Chinchilla chinchilla). This rodent was once distributed across the central Andean highlands from Bolivia and Peru into Chile and northern Argentina. Due to extensive hunting, its population declined dramatically and is now considered to be extinct over much of its historic range. Recent diet analysis has found that in many parts of its range, the Andean Mountain Cat is now feeding primarily on viscacha (Lagidium sp.), a species whose populations have increased markedly in the Sibinacocha watershed in recent years.This may indicate that the Andean Mountain cat and other rare carnivores (e.g. the Pampas cat) will continue to utilize, and perhaps thrive within the Sibinacocha watershed.
While hunting is a concern, it is just one of the threats facing mammal populations in this region. Habitat loss, degradation, and fragmentation due to mining, overgrazing, development, and unregulated tourism are considered to be the most immediate threats to both predators and prey. Another is the growing threat of climate change. The glaciers of the Sibinacocha watershed and surrounding area provide most of the available water in this otherwise arid environment, and these glaciers are melting. Native populations of plants and animals living there must either adapt to changing conditions or move to more suitable habitat. Species living at lower elevations can move to higher elevations as warmer temperatures cause their habitats to shift upward. However, species living at the highest elevations may be trapped due to the lack of suitable habitat or barriers to dispersal, leaving them vulnerable to extinction. Of the 6 large mammal species that may occur in this region, only 1, the culpeo fox, is not currently designated as endangered, vulnerable, or near threatened. Developing a conservation strategy for the region is key to their survival.
To to understand the impacts of these threats on mammal populations, we initiated preliminary mammal surveys in the Sibinacocha watershed in 2000. Rodent surveys conducted in 2000, 2001, and 2005 resulted in the documentation of 8 rodent species in 5 genera (Auliscomys boliviensis, Auliscomys pictus, Chinchillula sahamae, Abrothrix jelski, Phyllotis osilae, Punomys kofordi, Calomys lepidus, and Lagidium peruanum). In 2014, we deployed camera traps at 3 locations. Since then, the cameras have photographed puma (Puma concolor), pampas cat (Leopardus colocolo), culpeo fox (Lycalopex culpaeus), vicuña (Vicugna vicugna), and the taruca or Andean deer (Hippocamelus antisensis), most at elevations exceeding 17,000 ft (5,200m).
Additionally, we have observed tracks that may be of the endangered Andean Mountain Cat (Leopardus jacobita). Documenting the presence of this species is of particular importance. It is one of the top five most endangered cats in the world and very little is known about its distribution, especially in the Cordillera Vilcanota where its existence has be documented only once in an adjacent watershed.
Beginning in 2018, we plan to deploy camera traps in several locations throughout the Sibinacocha watershed and surrounding drainages to determine the distribution, relative abundance, and habitat use of carnivores in the region with particular emphasis on documenting the presence of the Andean Mountain cat. Additionally, we will collect carnivore scat for DNA and diet analysis. This information will help us understand the degree of population isolation, and habitat and prey associations.
Surveys will also be conducted to document rodent species distribution, abundance, and habitat use to determine potential prey base for carnivore populations. Baseline rodent surveys will also lay the foundation for more extensive, long-term studies to document shifts in animal communities in response to rapid climate changes. Because the Sibinacocha watershed is one of the world’s most extreme and threatened environments, understanding the impacts of these threats on the region’s significant biodiversity may be key to predicting the impact of global climate change on montane ecosystems world-wide.