Bears of the Himalayan Mountains

[Sully]

Projected climate change threatens Himalayan brown bear

habitat more than human land uses

Abstract


Climate change and land use change jointly are the largest drivers of population

declines, range contraction and extinction for many species across the globe. Wide-

ranging and large-bodied species are especially vulnerable to habitat loss and frag-

mentation due to their typically low population densities, reecting their need for

extensive and connected habitats. We used the multi-scale Random Forests

machine learning algorithm to identify factors driving the habitat selection and

future changes in habitat of Himalayan brown bear, an iconic wide-ranging and

large-bodied species of high conservation interest, across a range of spatial scales.

Habitat selection of brown bears was scale-dependent, with most variables selected

at broad scales. Climatic variables such as maximum temperature of coldest month,

minimum temperature of warmest month and the potential evapotranspiration of

wettest quarter strongly inuenced habitat selection of brown bears. Future projec-

tions indicate a strong difference between the high and low emission scenarios.

Alarmingly, our model suggests that high emission scenarios, with or without land

use change, may result in a decline of brown bear habitat of >90% by the end of

the century. In contrast, low emission scenarios are projected to reduce brown bear

habitat by <23%, with much of the species range shifting to higher elevations. This

study provides an integrative understanding of scale-dependent variables in brown

bear habitat selection, providing critical information for prioritizing areas for habitat

management and conservation. Most importantly, our future projections imply that

traditional conservation efforts, such as in situ conservation, will not be sufcient

to protect the species without climate change mitigation. The incorporation of cli-

mate change mitigation and adaptation in conservation strategies will be one of the

most pressing priorities in biodiversity conservation in this region. Reply