Animals are increasingly changing because of the climate crisis, researchers say.
Scientists discovered that warm-blooded animals changed their physiology to adapt to hotter climates. These include larger beaks, legs, and ears to better regulate their body temperature.
When animals overheat, birds use their beaks and mammals use their ears to distribute heat. Some creatures in warmer climates have evolved in the past to have larger beaks or ears to make it easier to dissipate heat. This difference becomes more pronounced as the climate warms.
If animals cannot control their body temperature, they can overheat and die. The beak that is not covered with fur and therefore is not insulated is a significant site of heat exchange, as are the ears, tail, and feet of mammals when they are not covered with fur.
The study, published in the journal Trends in Ecology & Evolution, found that the difference was particularly pronounced in birds.
Study author Sara Ryding of Deakin University, an ornithologist, said, “Changes in shape don’t mean animals can cope with climate change and all is well.
“It just means that they evolved to survive — but we’re not sure what the other ecological consequences of these changes will be, or that all species can change and survive.”
While scientists say it is difficult to pinpoint climate decline as the sole cause of shapeshifting, the cases studied share features in common across all geographic areas and across different species.
Examples include several species of Australian parrots which have shown a 4-10% increase in beak size since 1871, which is positively correlated with summer temperatures each year.
Meanwhile, research on North American dark-eyed juncos, a type of small songbird, showed an association between increased beak size and short-term temperature extremes in cold environments.
Researchers have also reported an increase in tail length in wood rats and an increase in tail and paw size in masked rats. Bats have been shown to have larger wing sizes in warmer climates.
The paper argues that shapeshifting is likely to continue as the climate warms. It said: “The increase in temperature associated with climate change is likely to affect thermoregulatory requirements in animals, among other things.
“The increase in temperatures experienced as part of climate change could result in the selection of larger appendages that allow efficient heat dissipation or the relaxation of options for small appendages that can adversely affect body heat loss in cold climates.”
While the change is small, Ryding says it could change as the planet gets warmer.
“The appendage size increase we’ve seen so far is small enough — less than 10% — that the change is unlikely to be felt right away,” he said. “However, it is expected that protruding frills like ears will increase so we could end up with live-action Dumbo in the not too distant future.”
Ryding intends to study the changing shape of Australian birds firsthand by scanning museum bird specimens from the last 100 years to see which birds have changed the size of their appendages due to climate change.
“When climate change is discussed in the mainstream media, people often ask, ‘Can people get over this?’ or ‘What technology can solve this?’ It’s time we realized that animals also needed to adapt to these changes, but this happened over a much shorter period of time than most evolutions,” said Ryding.
“The climate change we’re causing is putting tremendous pressure on them, and while some species will adapt, others won’t.”
It’s unclear whether these changes will affect the animals in other ways — for example, a larger bill could affect bird feeding, which the scientists plan to investigate in future work.
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