Pigeons can tell the difference between healthy tissue and a tumor, and they might be able to sit in for humans doing some of the more boring chores in a pathology lab, researchers said Wednesday.

They’re especially eagle-eyed when it comes to diagnosing breast cancer, it seems, the researchers report in the Public Library of Science journal PLoS ONE.

They flunk out on reading mammograms, however, so don’t look for the birds to be replacing human specialists any time soon, the teams at the University of Iowa and the University of California Davis said.

"Our results suggest that pigeons can be used as suitable surrogates for human observers in certain medical image perception studies."

"The birds were remarkably adept at discriminating between benign and malignant breast cancer slides at all magnifications, a task that can perplex inexperienced human observers, who typically require considerable training to attain mastery," said Richard Levenson, a professor of pathology and laboratory medicine at UC Davis Health System who worked on the study.

“Pigeons' accuracy from day one of training at low magnification increased from 50 percent correct to nearly 85 percent correct at days 13 to 15."

Levenson and colleagues decided to train pigeons after they saw a long history of studies showing they can detect patterns pretty well.

"Research over the past 50 years has shown that pigeons can distinguish identities and emotional expressions on human faces, letters of the alphabet, misshapen pharmaceutical capsules, and even paintings by Monet vs. Picasso," said Edward Wasserman, a professor of psychological and brain sciences at the University of Iowa who worked on the study.

"Their visual memory is equally impressive, with a proven recall of more than 1,800 images."

They trained the birds to tell the difference between healthy tissue and tumor tissue as displayed on the slides that pathologists use to look at biopsies in the lab. The birds peck a colored square in a computer screen to show when they’ve decided whether a sample is cancer or benign tissue.

To make sure the pigeons weren’t just memorizing pictures, the team showed them a batch of new images they’d never seen before. They passed the test with flying colors.

But the birds did even better when their efforts were crowdsourced. The researchers put together the efforts of four birds and called it a “flock score”

“The resulting ‘group’ accuracy level reached an amazing 99 percent,” they wrote.

"These results go a long way toward establishing a profound link between humans and our animal kin."

However, weeks of training the birds to read mammograms turned out to be a waste of time. The pigeons seemed to do well in detecting the so called microcalcifications that are a sign of early tumors. But when the team swapped in never-before-seen mammograms, it became clear the birds had just memorized what they needed to know to get the training rewards.

So what could the birds be good for? Maybe testing new computer displays that will replace the task of peering through microscopes, the researchers suggested.

“Overall, our results 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 as subjects for relatively mundane tasks,” they added.

Edward Wasserman of the University of Iowa and one of his pathologist pigeons University of Iowa

"These results go a long way toward establishing a profound link between humans and our animal kin," said Wasserman. "Even distant relatives — like people and pigeons — are adept at perceiving and categorizing the complex visual patterns that are presented in pathology and radiology images, surely a task for which nature has not specifically prepared us."