Robot Twitcher to Scan Skies for Rare Bird

The world's first robot twitcher has joined the hunt for the ivory-billed woodpecker. The device's inventors hope it will come up with the first hard evidence for the elusive bird's existence, and say it could monitor other rare species.

Hopes in the world of ornithology had been raised in 2004 by a tantalising video apparently showing an example of the ivory-billed woodpecker, previously believed to have died out in the 1930s in swampy forest in the south-eastern US.

But researchers could not agree on whether the blurred images were the real thing or a similar species, the pileated woodpecker. To settle the issue, a robotic bird-watcher will scan the skies continuously in the hope it will crack the "holy grail of bird-watching" with video proof.

"A single photographic frame would have to clearly show the unique markings of the ivory-billed woodpecker," said Ken Goldberg at the University of California, Berkeley.

"Much better would be a high-resolution video clip that would also capture its unique wing and flight patterns."

The system is a high-resolution digital camera pointed at the sky in the Cache river national wildlife refuge in Arkansas which records 11 two-megapixel images a second. It sifts the images for ones containing birds, and throws out the rest so as not to clog up its hard drive.

"The challenge is to develop the software that can process the images in real time to throw out everything that is not a bird," said Prof Goldberg.

The camera looks for rapid changes from one image to the next in a small area of the field of view. If these have an irregular shape and are moving at flying speed, the robot twitcher keeps them for researchers to look at later.

It has captured a red-tailed hawk, a great blue heron and a flock of Canada geese; but so far there has been no sign of the ivory-billed woodpecker.