They quickly learnt to tell the two apart, and within a fortnight were 85 per cent accurate. Remarkably, the birds performed just as well when given an entirely new set of images. This showed they were not relying on memory but had learnt some of the basics of pathology.
Pigeons were also trained to spot the white specks that are a sign of cancer on mammograms, the specialised X-ray tests regularly carried out on women from the age of 50.
While the birds were as good at this as the trained radiographers who analyse X-rays, they found it more difficult to accurately detect suspicious tissue masses on scans.
They might not put radiographers out of work, but pigeons could still be used. For instance, companies developing software for medical imaging could employ the birds, rather than doctors, to do some of the necessary but repetitive testing, the journal PLOS ONE reports.
Professor Edward Wasserman, a researcher at the University of Iowa, said: "These results go a long way toward establishing a profound link between humans and our animal kin.
"Even distant relatives - like people and pigeons - are adept at perceiving and categorising the complex visual patterns that are presented in pathology and radiology images."
Previous research has shown pigeons are capable of recognising letters of the alphabet, learning facial expressions and even distinguishing Picasso paintings from Monets.
- Daily Mail