Tiny cameras attached to New Caledonian crows' tail feathers are offering new insights into the birds' behaviour in the wild.
The crows, famous for their impressive tool-making and using abilities, are also notoriously difficult to observe in their native environment because they live in forests and are very shy.
Working together with Jonathan Watts, who has previously constructed cameras worn by eagles for the BBC television series Animal Camera, Christian Rutz and colleagues from the University of Oxford developed cameras weighing only 14 grammes that can be worn by the crows without disturbing their natural behaviour.
"We attach the camera to the tail feathers so the lens pokes out under the belly," says Rutz. "This allows us to see the crow's head whenever it bends forward."
The camera also contains a simple radio transmitter that reveals the crows' location. This lets the researchers track them at a distance of few hundred metres, so that they can catch the camera's video signal with a portable receiving dish.
Up to 70 minutes of footage can be broadcast by the camera's chip, and the camera is shed once the bird moults its tail feathers.
New insights
Rutz and his team obtained video from 12 camera-tagged crows that showed them making, using and transporting tools; eating fruit, snails and lizards; and interacting with other crows.
"We can now observe when exactly these animals really use tools in the wild, which will help us to understand why and how their tool-making skills evolved," says Rutz. Due to its position underneath the tail, the cameras could also provide insights into the animals' physiology. "The rise and fall of the belly tells us their breathing rate, and we even see when the birds defaecate," Rutz explains.
Nicola Clayton, who studies social intelligence in jays and rooks at the University of Cambridge, is excited by the new technology. "With animals that are shy or hard to observe, this really offers a pair of new eyes. Food caching, for example, is a secretive behaviour – with these cameras we could observe in the wild what we can normally only study in the lab."
http://www.newscientist.com/article/dn12738-shy-crows-tool-use-caught-on-camera.html
