Nitrogen metabolic wastes do not influence drinking water preference in feral pigeons

Pathogens of both avian and mammalian fecal origin can infect birds via drinking water. Since birds often use ultraviolet clues for many decisions such as food detection, they may also be able to distinguish between faeces- or urine-polluted water and clean water by using UV vision. Here we test the hypothesis that birds may assess potential pollutions in drinking water bodies using UV absorptions/reflections. Feral pigeons were offered with (1) clean tapwater, (2) uric acid polluted water (UV-absorbant) to mimic wastes of avian origin and (3) urea solution (UV- reflectant) to mimic wastes of mammal origin. Contrary to our expectations, pigeons exhibited no detectable preferences in double-choice experiments.