Claws and effect: Birds talented with their talons share common ancient ancestor

From parrots to raptors, birds that demonstrate dexterity with their claws share a common ancient ancestor, new research suggests.

A study from the University of Alberta, published Aug. 15 in the journal Communications Biology, examines the evolution of bird bodies — namely, their feet.

Researchers aiming to better understand how the brains of these birds are different from their less-dexterous counterparts turned bird-loving shutterbugs into citizen scientists. 

Relying on thousands of images shared by birders on the internet, researchers investigated how some birds became more talented with their talons — and how the world's first birds gave rise to the diversity of bird species we know today. 

Cristian Gutiérrez-Ibáñez, a U of A neurobiologist and the study's lead author, said when birds evolved to have wings, those limbs were no longer useful for eating, climbing or caring for their young.

Researchers were interested in finding out why some species developed better claws.

"Birds use their beaks to manipulate objects," Gutiérrez-Ibáñez said in an interview. "But it's hard to open a jar with one hand, right?

"The same thing is true for cracking a nut or eating mice. And so, they started using the only thing they had left, which is their feet.

"We wanted to understand what drives the evolution of that."

The study of more than 1,000 species found that all birds that use their feet for tasks other than perching are part of a large-brained clade of birds known as core land birds or Telluraves. A clade is a large group of species that all trace back to a common ancestor.

The findings suggest that birds made better use of their feet, not just their beaks, as they adapted to grasping branches in the forest canopy.

It all began 60 million years ago, when the clade's common ancestor, likely a predator, moved from the forest floor to the trees.

Just like modern tree-dwelling birds, early birds of the Telluraves clade had long back toes that would have worked almost like a thumb for clasping. They also had toe tendons that provided them stronger holds on perches.

The study found the family tree diverged repeatedly through the generations as birds adapted to their diet or surroundings. Adaptations happened at least 20 times, the study found, as birds further specialized their footwork for tasks like cracking nuts or clawing at prey.