Climate change is already causing physical changes to animals

Several animals already have larger beaks, legs and ears to better regulate their body temperature. But whether that also increases their chance of survival…

Climate change is not just a human problem. Animals also have to adapt. And that over a much shorter time frame than evolution normally takes for climate change. Yet nature seems to be doing its job. For example, scientists have already spotted various physical adaptations in some ‘warm-blooded’ animals quite early in the climate crisis. Still, in a new study, researchers are far from reassured.

birds

Researchers have noted “metamorphosis” especially among birds. For example, several Australian parrots have grown beaks since 1871. The size of their beaks increased on average between 4 and 10 percent. This was positively correlated with summer temperature each year. But not only in Australia, birds are adapting. A cute North American songbird – the gray junco – also appears to be subject to change and now has a larger bill.

Larger beak

The fact that these birds get a larger beak is also easy to explain. “Bird’s beaks play an important role in dissipating excess body heat,” researcher Sara Ryding explains Scientias.nl from. “It is therefore logical that they become larger in order to create more surface area to lose heat. In addition, birds are able to regulate blood flow to the beak, allowing them to more accurately determine how much heat is lost through the beak.” And that is a very efficient way. “For example, if they respond to climate change by losing feathers, they wouldn’t be able to determine how much heat is lost,” Ryding clarifies. “Ultimately, shape change is about very basic physics: a better ratio between surface area and volume.”

Mice

But it’s not just birds that seem to be adapting to new conditions. Some mammal species, including the wood mouse and the American masked shrew, are already doing this. For example, researchers have found that wood mice have increasingly longer tails. The shrew has both a longer tail and larger legs. “These larger tails (just like the beaks of birds, ed.) provide more surface area from which body heat can escape,” explains Ryding. “The cause of the differences between the wood mouse and the shrew is not yet entirely clear. But it is possible that shrews use their legs more often to lose heat than wood mice.”

The increase in the size of the limbs is still quite small, less than 10 percent. “It is therefore unlikely that these changes will be noticeable immediately,” Ryding says. “However, it is predicted that prominent appendages – such as ears, for example – will also increase in size. So it is possible that in the not so distant future real Dumbos will arise.”

You might think that these observed transformations in animals are good news. They seem to be successfully adapting to the future warmer climate. Still, Ryding is cautious. “It’s hard to say if it’s a good or a bad thing,” she says. “On the one hand, it does indeed imply that animals evolve in response to climate change and thus try to survive. On the other hand, we do not yet have data to confirm that the observed physical changes actually help populations to survive. Physical change therefore does not mean that animals deal with climate change and that all is well. It simply means that they evolve to survive. Whether that works is another matter.”

Winners and losers

We know that climate change has winners and losers. On the one hand are the animals that successfully adapt to changes in their living environment and in this way secure their future. On the other hand, climate change has losers; the animals that bounce too slowly and thus approach their demise. Whether the birds and mice described here will be counted as winners or losers remains to be seen. “I think there will be overwhelmingly many losers overall,” Ryding says. “And I think the animals discussed here are also mostly losers. It is very alarming that animals are being forced to change their morphology so early in the climate crisis. The climate may be changing faster than species can evolve. And in that case, the risk of extinction continues to increase. While some (not all) species are already adapting, we don’t know if animals can keep up as the climate crisis continues to worsen.”

Climate change therefore puts a lot of pressure on all animals. And while some will be able to adapt successfully, others will unfortunately fall short. The researchers plan to continue their study to better understand which birds will change further as a result of climate change and how that will unfold. “What surprised me most about this study is how widespread the phenomenon is,” Ryding says. “The examples include mammals and birds, spread from Alaska to Australia. It’s unbelievable and scary how widespread this seems to be. So we have to keep studying it to learn more about it.”