Diving birds more likely to go extinct, new study finds

Diving birds like penguins, puffins and cormorants may be more prone to extinction than non-diving birds, according to a new study from the Milner Center for Evolution at the University of Bath. The authors suggest that this is because they are highly specialized and therefore less able to adapt to changing environments than other birds.

The ability to dive is quite rare among birds, with less than a third of the 727 species of waterbirds using this method of hunting for food.

Evolutionary scientists Joshua Tyler and Jane Younger studied the evolution of diving in modern waterbirds to study the impact of diving on: birds’ physical characteristics (morphology); how species have evolved to increase diversity (speciation rate); and how prone the species was to extinction.

The study, published in Proceedings of the Royal Society Bfound that diving evolved independently 14 times and that once a group evolved the ability to dive, subsequent evolution did not reverse this trait.

The researchers found that the body size of diving birds evolved differently depending on the type of diving performed.

Winged divers, like penguins and puffins, use their wings to propel themselves through the water. These birds tend to have larger bodies, adapted for swimming.

“Walk-diving” birds, like cormorants, kick to swim and are just as larger in size than winged divers.

In contrast, “divers,” such as gulls and gannets, dive vertically from the air to catch their prey. Researchers found that these species tended to be more limited in their body size, as they were better adapted to flying than swimming.

Although the research found no significant differences in the rate of speciation between diving birds and non-diving species, they also found that many diving birds appeared more prone to extinction than non-diving species.

The techniques used by the researchers could be used to help conservationists predict which species are most at risk of extinction from an evolutionary perspective.

Josh Tyler, first author of the paper and a PhD student at the Milner Center for Evolution at the University of Bath, said: “Our work shows that rather than being a random process, there are predictable patterns of evolution.

“Waterbirds were grouped together as highly related following genetic analysis of the birds’ family trees in 2015. So I wanted to study how evolution to be able to dive had affected their body shape, their adaptation to the niche and their evolutionary diversity.

“For example, penguins are very adapted to their environment: they have a torpedo-shaped body that helps them swim quickly, but they don’t fly and they can’t move very well on land.

“This means they cannot easily adapt to other environments or diet types. In contrast, divers like gulls are more generalists – they eat everything from fish to Cornish pasties – and we’ve found that they explode in diversity.

“Our data show that specialized birds are in more trouble in terms of future extinction and could be moving toward an evolutionary dead end.”

Researchers hope the study can help inform conservation work, predicting which species are most likely to be at risk in the future.

The study was funded by the University of Bath and a grant from the Evolution Education Trust.

Thanks to the University of Bath for this news.