Crowberry is common in most of the shrub-heath communities on Sable Island. In autumn, the plant’s blackish berries are eaten by Herring Gulls. Small groups of gulls wander through the vegetation and seek out the fruit, and then deposit splats of purple on the Station’s boardwalks. The elegant purple hue arises from a mix of pigments from the ingested crowberries with the white component (urea crystals) of the birds’ normal excrement.