Larger Animals Can Better Handle Climate Change

Climate change places all living things in an unwitting game of “Survivor.”

As extreme weather events—like prolonged droughts and heat waves—continue to get worse, animals are affected in different ways. A new study finds that certain characteristics have an impact on how mammals survive.

“I was interested in whether trends that could be linked to species characteristics could be seen in population responses to weather,” says researcher Owen Jones of the University of Southern Denmark. “If so, these simple patterns could be useful from a management and monitoring perspective because they could help us predict which species are likely to be more affected by changing weather patterns.”

For their research, scientists considered how population size each year changed in relation to the weather during those periods. They analyzed data on these population fluctuations from 157 mammal species around the world.

They then compared that data with weather and climate data from the time the information was collected. They had at least 10 years of data for each species.

“Specifically, we used ‘anomalies,’ or departures from the long-term average, in the temperature and precipitation (rainfall),” Jones says. “For example, one might expect a sharp dip in temperature to lead to a decline in the population from one year to the next as the population suffers over the winter.”

Why Size Matters

In their analysis, researchers found that their responses to weather changes were associated with relatively simple characteristics. Species with long life spans who have fewer offspring were more resilient to weather changes than smaller animals that have a large litter.

Larger animals like bears and elephants can use their energy to focus on a sole offspring or wait for better conditions before reproducing.

Smaller, short-lived animals like rodents, however, don’t have that luxury. If there’s a long drought much of their food source (flowers, insects, fruit) can disappear quickly and they don't have the fat reserves that would allow them to wait out challenging weather conditions.

Researchers found that some of the mammals most affected by extreme weather include the Canadian lemming, Arctic fox, common shrew, and several species of mice.

Some of the animals least affected include the African elephant, Siberian tiger, chimpanzee, white rhinoceros, and American bison.

The results were published in the journal eLife.

Informing Conservation Decisions

Researchers say the results are important because they offer some simple ways to predict how species will respond to climate change.

Knowing that a mammal’s size and its litter size have an impact on how they withstand weather anomalies, can also give insight into little-known animals.

Even if there is little data on an animal’s population, knowing these characteristics can help predict how it will respond to ongoing climate change.

And the information is one more tool when making conservation decisions.

“In particular the results suggest that smaller ‘fast’ species might need special conservation attention in areas where weather patterns will get more unpredictable because these are the species that are less resilient to weather ‘shocks,’” Jones says.

“The paper also highlights that we don’t have enough monitoring in place: Just 157 species with enough data for our analysis (out of circa 5,000 mammal species). We would therefore encourage a shift towards more intensive monitoring of species in general, and in particular in regions where weather patterns are changing the most.”