You may think penguins all look the same, but a computer system on a South African island knows better. It can identify individual birds from subtle differences in their plumage.
The technology could help researchers monitor threatened populations without using more invasive methods that can distress or harm the birds.
There were 1 million African penguins at the beginning of the 20th century, but that number has plummeted to around 170,000.
Studying the remaining penguins is important to conserve the population, but the usual practice of tagging flippers with metal bands can reduce breeding performance and human contact stresses penguins.
Tilo Burghardt and Peter Barham, both at the University of Bristol, UK, think their remote camera system is the answer.
The camera can identify individuals from the unique black chest markings on each bird and is currently being tested on the 20,000 African penguins on Robben Island, South Africa (see video, right).
Bird spotter
The camera is hidden at ground level on a path the penguins use to reach the sea each day. Footage is sent to a computer running software that is able to identify individual penguins by looking for the distinctive black spots on the African penguins' chests.
If a bird is not in full view it abandons the ID attempt, but when the chest is clearly visible the software generates a 2D map of the black plumage spots and compares this with a database of stored maps.
If a match is found the bird can be identified, if there are no matches the new map is added to the database. The software has been designed take into account the way a penguin's spots can change subtly as the bird breathes and moves.
To ensure that penguins with similar markings were not confused by the system, it was calibrated by analysing the variation in how one bird's pattern can appear on camera, and the variation between different birds' patterns.
Flighty nature
"The identification rate is now about 98% accurate with very few false positives," says Burghardt, adding that once installed the system is ignored by the penguins.
"You don't realise how much you can affect the birds just by going to within 100 metres of them," adds Barham.
The camera system could be used to track the overall population, because over the course of a month the computer should snap every bird that uses a path at least once.
It should also be possible to track behaviour of individual birds, for example the way male and female birds share chick guarding and fishing trips. Barham even thinks it possible to judge how much a bird has eaten by the way its stomach contents stretches its spots.
Problem plumage
Katie Dugger at Oregon State University in Corvallis, Oregon, US, likes the idea. "I think it shows great promise for penguin species that have distinctive markings," she says, adding that not all penguins are identifiable in this way.
But Jaume Forcada at the British Antarctic Survey in Cambridge, UK, says exhaustive trials will be needed to verify its accuracy.
"My experience working with whales, dolphins and seals is that of all natural marks, [plumage] patterns are the most difficult to match," he says. "In many cases a slight change in angle between penguin orientation and camera lens can make a difference."
Tidak ada komentar:
Posting Komentar