Mammals With Fewer Young Are More Resilient Against Extreme Weather, Study Suggests

Longer-lived mammals with fewer young are better able to cope with extreme weather, according to a new study.

“We can see a clear pattern: Animals that live a long time and have few offspring are less vulnerable when extreme weather hits than animals that live for a short time and have many offspring,” Owen Jones, a biologist at the University of Southern Denmark and co-author of the study, said in a statement. “Examples are llamas, long-lived bats, and elephants versus mice, possums, and rare marsupials such as the woylie.”

For the study, scientists tracked how populations of 157 different mammal species responded to periods of heavy rainfall, drought, and other shifts in climate. Overall, they analyzed 486 population records spanning 10 years or more.

Their analysis found that long-lived mammals with few offspring fare better against extreme weather as they can wait until conditions improve to reproduce or they can focus their care on a single young. Examples include African elephants, Siberian tigers, chimpanzees, llamas, vicuñas, white rhinos, grizzly bears, and American bison.

Shorter-lived mammals that produce a greater number of offspring are more vulnerable to extreme weather, the study found. A long drought or intense flood may decrease the supply of insects, fruits, and other foods, leaving large numbers of young to starve. Vulnerable creatures include olive grass mice, Canadian lemmings, Tundra voles, Arctic foxes, common shrews, and Arctic ground squirrels.

While these same species may see their numbers grow quickly in favorable conditions, climate change is producing more extremes, posing a long-term challenge. As temperatures rise, “fast” species “may require particular conservation attention, to avoid extinction due to the increased frequency and magnitude of extreme events,” the study said. The research was published in the journal eLife.

Authors were careful to point out that “slow” mammals are not necessarily less vulnerable to severe climate change. While they are better able to endure short bouts of extreme weather, they may struggle against consistently challenging conditions.

Large mammals also face numerous other threats to their survival, said the study’s lead author, John Jackson, a postdoctoral researcher at Oxford who undertook the study while at the University of Southern Denmark. He said, “Habitat destruction, poaching, pollution and invasive species are factors that threaten many animal species — in many cases even more than climate change.”

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