As the planet warms, animals living in tropical mountains may find it increasingly difficult to shift to new areas, according to a new study.
Tropical mountains are particularly at risk when the impacts of climate change combine with changes in land use and human pressures, Chiara Dragonetti, co-author of the study published in June, told Mongabay in a video call.
Many mountain-dwelling species are endemic to those areas and can only tolerate climatic conditions within narrow limits, researchers have previously found. Higher altitudes may be the right temperature but the wrong habitat, and species already living at high altitudes can only shift so high. Eventually, animals can run out of safe space on a mountain in a pattern scientists have dubbed an “escalator to extinction.” Changes in how mountain land is used can further limit animals’ movement.
Dragonetti wanted to understand how mountain wildlife will fare in a warming world, while also considering land-use changes and the species’ dispersal abilities. She and her colleagues analyzed existing global datasets of distribution for 395 different mountain-dwelling species, including 361 birds and 34 mammals, breaking them down by animals that can easily disperse, such as birds, and those that can’t easily relocate, such as sloths. They then used computer models to project where these species could occur in 2050, under future high and low greenhouse gas emissions scenarios.
The study found that under a high emissions scenario, wildlife would lose 16% more range (or places they can live) compared to a low emissions scenario.
“For a mountain species, the 16% is a big number actually, because most of the species are endemic,” Dragonetti said. Some 112 of the 361 bird species and 15 of the 34 mammal species are endemic to their region, the study says. Because many of these species exist only on a single mountain or a small mountain range, losing even a modest portion of their habitat could significantly increase their risk of extinction, Dragonetti added.
While climate change is the biggest factor in the need to move for mountain-dwelling animals, the study says land use change and the availability of habitat are significant in determining where the animals can go.
Tropical mountains are expected to experience much more land-use change than mountains in Europe or North America. Models that also included land-use data showed that mountain-dwelling wildlife in Central and South America and Oceania will be most at risk.
Ability to disperse also matters: More birds will be able to disperse, or move to a new range, than mammals by 2050, the study found. However, Dragonetti cautioned against drawing broad conclusions with a dataset of just 34 mammal species.
The authors say their study underscores the need to protect mountain habitats now and that their findings can “identify climatic refugia to understand where species will be safer.”
Banner image: Costa Rica’s Arenal Volcano at the foothills of the Cordillera de Tilaran mountain range. Image by Bobby Bascomb/Mongabay.
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