Arstechnica:

Though we’ve long known that crows use tools to get food (and occasionally to amuse themselves), scientists have lacked definitive evidence. Which is why two intrepid researchers invented the crow tailcam, to record the inventiveness of these birds in the wild.

UK researchers Jolyon Troscianko and Christian Metz had observed crows making tools in the wild, as had some of their colleagues. But none of them ever caught this amazing feat of intelligence on video. A couple of years ago, Metz co-authored a paper about how crows make hooked tools, carefully fashioning them out of branches, in order to get at hard-to-reach grubs inside a piece of wood. But he was quick to point out that those feats of tool-making were done in captivity—where animals often develop a penchant for tool-making that they wouldn’t have in the wild. In a paper out last week from Biology Letters, however, Troscianko and Metz describe how they finally caught wild crows making their hooked tools on video.

Not to put too fine a point on it, they put cameras on the crows’ butts. More precisely, they used biodegradable rubber to attach tiny cameras to the birds’ two strongest tail feathers, giving the researchers a below-the-belly view of the crow’s activities. Because crows often lower their heads to foot level to eat and make tools, this was also an excellent vantage point to capture tool-making in action.