Already endangered due to threats such as poaching and retaliatory killing, the snow leopard is also likely to be adversely affected by climate change. With temperatures and precipitation expected to rise in the Himalaya, the snow leopard’s preferred alpine habitat may be overrun with forests due to shifts in treeline range. To estimate the potential effects of alpine loss, Forrest et al. (2012) mapped current snow leopard habitats and monitored their responses to various climate change scenarios from 2070–2099. Depending on the severity of emissions, 10–30% of snow leopard habitat could be lost, potentially isolating populations of snow leopards in eastern China and northern India. The increase in forested areas may also add further adverse effects by increasing resource competition with the introduction of additional predatory species. Human activity is also likely to displace snow leopard prey, increasing the risk of snow leopards being killed by herders if they are forced to hunt livestock. The authors suggest that potential conservation efforts should account for such influences by human activity and that actions be concentrated in areas resilient to climate change, where populations are likely to remain intact.—Katie Huang
Forrest, J.L., Wikramanayake, E., Shrestha, R., Areendran, G., Gyeltshen, K., Maheshwari, A., Mazumar, S., Naidoo, R., Thapa, G.J., Thapa, K., 2012. Conservation and climate change: assessing the vulnerability of snow leopard habitat to treeline shift in the Himalaya. Biological Conservation 150, 129–135.
Forrest et al. used snow leopard observation data, published literature, and expert opinions to map snow leopard habitats. They defined potential habitats as grassland, shrubland, bare areas, or agricultural mosaic in rugged alpine regions below an elevation of 5500 m. Forest regions and areas with an altitude above 5500 m were not considered to be likely habitats for snow leopards, assumptions they confirmed with observational data. To examine the relationships between different blocks of habitat, the authors determined the dispersal range of snow leopards by modeling their costs of movement. In order to estimate the effects of climate change on the habitat regions, Forrest et al. identified four independent variables that were found to influence the treeline and created a logistic regression model. With its use, they analyzed changes in alpine zones under low, medium-low, and high emissions scenarios, using projected precipitation and temperature values from 2070–2099 that account for a wide range of plausible future climates. However, due to data limitations in regards to factors such as local weather patterns and rate of soil formation, the authors consider their model only to be a potential map under the conditions of adequate prey and limited human impact.
The authors found that their model had a 98% chance of predicting alpine zone accurately. With its use, they estimated a current habitat of 217,000 km2, most of which is in large interconnected habitat blocks. Under a high emissions scenario, about 30% of the current habitat range is threatened. Habitat blocks were found to likely decrease and become smaller on average, potentially isolating parts of the snow leopard population in eastern China and northern India. Most of the loss would occur in the southern area of the snow leopard range and in deep river mountain valleys. Under low emissions scenarios, up to 10% of habitat could still be lost. However, a large population of snow leopards along the southern border of China is likely to remain intact and may accumulate populations pushed northwards from Bhutan, Myanmar, and Nepal. In light of these results, the authors suggest that regions with resilient populations of snow leopards that are less vulnerable to climate change should be the focus of conservation actions.
If snow leopards are unable to adjust physiologically and ecologically to climate change, they may be also be impacted by other effects associated with a shift in treeline. The movement of forests may introduce other predatory species to the area, intensifying competition for limited resources. As a result, snow leopards might be driven upward past a 5500 m altitude, and the resulting decrease in oxygen would likely hurt their ability to hunt and survive. Changes in human behavior may also affect snow leopard habitats. As herders shift their livestock from nomadic to sedentary grazing, alpine grasslands become more quickly depleted. Combined with an increased harvest of native plants for medicinal and aromatic purposes, the loss of snow leopard habitats may be greater than expected. Human interactions can also potentially harm snow leopard prey species as they become displaced by livestock or eliminated as resource competition, forcing snow leopards to feed on livestock and putting them at risk of retaliatory killing by herders. As the effects of climate change include human-influenced dangers as well, Forrest et al. advise that both ecological and anthropogenic effects should be incorporated into any potential conservation actions.
Although their model was designed specifically for snow leopards, the authors suggest that it can also be applied to umbrella species in order to prioritize areas in need of conservation. They further recommend their treeline model as a means of predicting potential shifts in other regions of the world.