As the solving of art mysteries go, it is certainly one of the more unusual clues.
But a century-old question over who painted a gift from Queen Victoria to her husband Albert has been solved, thanks in no small part to pigeon tendons.
The painting, Portrait of a Lady and her Son, was originally thought by Royal Collection experts to be by Franz Wolfgang Rohrich, merely one of around 40 imitations made in the mid-16th century.
Re-examination has now shown it to in fact be a work from Lucas Cranach the Elder, German Renaissance master and chief artist of the Reformation.
The reattribution, which will see the painting hung in Windsor Castle from today, came about as a result of careful scientific examination, including infrared reflectography, pigment analysis and an x-ray.
Among the key clues was the identification of fibrous material used to strengthen the painting’s panel, matched with other Cranach works DNA tested as pigeon tendon.