Clever Corvids: unique beaks for tool use (Introduction)

by David Turell , Tuesday, March 15, 2016, 20:11 (3175 days ago) @ David Turell

The finding that New Caledonian have a unique beak raises the old chicken/egg problem, beak first or tools first or saltation, both together:-http://phys.org/news/2016-03-unique-beak-evolved-tool-caledonian.html-"We used shape analysis and CT [computer tomography] scanning to compare the shape and structure of the New Caledonian crow's bill with some of its crow relatives and a woodpecker species with a similar foraging niche," said lead author Hunt.-"'This study shows that the unique bill contributes to the birds' ability to use and probably make tools," he said. "We argue that the beak became specialized for tool manipulation once the birds began using tools, and that this enhanced tool manipulation ability may have allowed the crows to make more complex tools."-"Such tools may range from sticks to barbed leaves or hooked twigs used to fish the crow's favorite food from the trunk of a tree - the juicy grubs of the longhorn beetle. The birds annoy their prey by poking around the grub's large, sensitive mandibles. When the grub grabs the stick or other tool, the bird hauls it out.-"'Their bill is shorter than a regular crow's," McGowan said. "It's blunter, and it doesn't curve down like nearly all bird bills do. The lower mandible actually curves slightly up, which likely gives it the strength it needs to hold the tool. And because the bill doesn't curve downward it brings the tool into the narrow range of the bird's binocular vision so it can better see what it is doing."-"Birds with blunter, straighter bills were probably more adept at handling tools for foraging and over time those features evolved, McGowan said. Tool use has now become ingrained in the crow's biology. In the case of the New Caledonian crow's beak, you might say it's not so much "you are what you eat," but "you are how you eat."-"'They hold the stick tool so that it goes up along the side of their head along the length of the bill," McGowan explains. "Apparently there are birds that favor one side of the head over the other—left-sticked or right-sticked, you could call it—it's really cool."-"The question that cannot be answered is why the crows started using tools in the first place. It may have been a matter of chance because most birds do just fine foraging with their beaks and feet without resorting to tool-making, McGowan said."-Comment: McGowan's point is the NC crows have a non-required phenotypic change. Why did it happen, or was it given?