New study proposes simple test to spot mammals most vulnerable to climate

A three-question test on nine South American rodent species could help scientists judge which small animals are most vulnerable to environmental change and which are best equipped to adapt to a warming world.

A team of six scientists in Argentina and Brazil who conducted the test said the method can be applied to other animals elsewhere on Earth, and updated with better information.

The findings were published in the latest issue of the international Journal of Zoology. Researchers at the Argentine Institute for Arid Zone Research in Mendoza, led by Emmanuel Fabián Ruperto, developed the method.

The other authors are his Argentine colleagues Josefina Menéndez, Fiona Alexandra Patterson, Agustina Novillo and Paola Lorena Sassi, and Brazil’s Marcial Quiroga-Carmona.

According to the study, global temperatures are expected to rise by between 1.5°C and 4.5°C by the end of this century, bringing more heatwaves and droughts. In the most severe warming scenarios, about 15% of species worldwide could face extinction, with wildlife in mountain regions facing a greater risk.

The scientists had limited data on the heat tolerance and population size of the small mammals they worked on. A reason was that about 30% of the world’s 2,700 rodent species have never received a formal risk assessment from the International Union for Conservation of Nature (IUCN).

They began observing nine chosen rodent species from Argentina and Chile to record their capacity to adapt to environmental change based on three fundamental behavioural traits: diel activity (a regular 24-hour cycle in the environment or an organism), habitat use and diet.

The answer to each trait-based question—when the species is active, how varied its habitat is, and how diverse its diet is—was scored from 0 to 2, giving a total of up to six. The scores were sorted into five categories, from “very strong” to “very poor” capacity to adapt.

The research revealed that the Phyllotis vaccarum rodent, flexible on all three counts, top-scored with six. The Abrocoma schistacea, which is active only by day, sticks to one habitat and has a narrow diet, scored zero. The other seven species scored 1 to 5, with the Necromys lilloi taking the mid-spot.

First guide

The authors said the scores offer a useful first guide as most of the nine species had either not been evaluated before or were data deficient. However, they said their scoring method was not meant to replace full vulnerability assessments, which also consider how exposed a species is to changing conditions and how sensitive it is to them.

They suggested their method could help decide which species needed urgent study, which might benefit from connected habitats or climate refuge and which need closer protection where they live.

“While we illustrate its application using rodent species from Argentina and Chile, the tool is broadly applicable to other taxa and regions,” the researchers said, suggesting that the tool could be relevant for many species occupying high-elevation environments.