Pigeons can be trained to detect what’s a cancerous tumour and what’s not

On a muggy summer day in Oakville, Ont., Mark Borges calls out to his feathered charges with whistles. It’s lunchtime, and that causes a lot of commotion in the pigeon loft.

“This is David Bowie,” says Borges, trying to calm the pigeon he’s just grabbed.  Named after the famed British rocker on the day he died, the avian Bowie is dark grey. The afternoon sun catches the magenta and teal feathers on its neck.

The eyes have it. A homing pigeon is held by its owner, Mark Borges of Oakville, Ont., who says pigeons are smarter than we think. A study shows pigeons can be trained spot cancer. (Kas Roussy)

‘Eyes like magnifying glasses’

“He’s got two different coloured eyes,” continues Borges.  “They’re like magnifying glasses.”  

Pigeons do have unusually good vision and now a study has shown they can use that sharp eyesight to distinguish benign tumours from malignant ones.  

Borges, a pigeon fancier, owns 37 pigeons and, when he’s not showing them off at exhibitions, he sells a few.

“If you’re feeding birds in a park, they’ll know when you’re coming. They’ll recognize you from quite a distance,” he says. “Tests have been done with people changing clothes and the bird will go to the person’s face that they recognize.

The pigeons trained in a chamber, equipped with a food pellet dispenser, and a touch-sensitive screen. Slide images showed up on the screen. (University of Iowa/Plos One)

Scientists have long known about the pigeons’ superior vision, noting the bird’s visual memory is also impressive and they are able to recall more than 1,800 images. In a study published last year in the scientific journal Plos One, researchers discovered that these “skilled observers” also can be trained to spot cancer.

A total of 16 pigeons were used for the study. In one experiment, the birds were placed in small boxes and shown slides of cancerous and non-cancerous breast tissue on a computer screen, with colour-coded panels.  The pigeons pecked a panel if they saw cancer and a different panel if they didn’t. A correct answer got them a food pellet.

Pigeons learn to detect cancer 

With this exercise, they correctly chose the right slide 85 per cent of the time over 15 days of training. “Remarkably, the pigeons rapidly learned to discriminate the appearance of benign from malignant breast tissue histology with high accuracy,” the study says.

As a flock, researchers found that when a group of pigeons were shown a full set of uncompressed images, the accuracy level reached “an amazing 99 per cent,” equivalent to trained human specialists.

In a second test, the pigeons were able to learn to classify whether micro calcifications (tiny calcium deposits in the breast, that can be associated with the presence of cancer) were benign or not with 50 per cent to 85 per cent accuracy over 14 days of training.

Pigeons were tasked to identify benign samples from malignant samples. In this test, they performed well, with a level of 85 per cent accuracy. (Plos One)

A third test involved determining whether breast tissue masses were benign or malignant.

“The one that really tripped them up were the X-rays of breast tissue masses that were either cancerous or not,” said co-author of the study, Ed Wasserman, a professor of psychological and brain sciences at the University of Iowa, in Iowa City.

“This is a very subtle distinction and, in fact, one that medical students have a great deal of difficulty with as well. In other words, the pigeons tended to have the most trouble with images that people have the most with because of the subtlety and difficulty of the task.” he told CBC News.

‘Jobs not in jeopardy’

Radiologists and pathologists need not worry about their jobs any time soon though.

“Their jobs are not in jeopardy,” says Wasserman.  But the authors suggest that “pigeons can be used as suitable surrogates for human observers in certain medical image perception studies, thus avoiding the need to recruit, pay and retain clinicians for relatively mundane tasks.”

Pigeon fancier Mark Borges shows off one of his pigeons at his home in Oakville, Ont. They may have a brain the size of a pea, but they have great visual memory. (Kas Roussy)

They might have a brain the size of a pea, but pigeon fancier Borges knows they’re smart, brave animals.”They’ve been around for thousands and thousands of years,” he says. They’ve been mentioned in the Bible and carried messages from the front lines of war.

• Pigeons Pathologists Learn to Detect Cancer CBC’s Quirks  Quarks

“They saved a lot of soldiers,” says Borges.  “They’re very intelligent.”

Professor Wasserman concurs. “The more we learn about animals, the more impressed we are about how smart they are and how much respect we should accord them.”