Preliminary investigations of ultraviolet-induced markings on domestic turkey chicks and a possible role in injurious pecking.

Several gallinaceous species including domestic turkeys have the capacity for ultraviolet (UV) vision. This might function in signalling between birds, for example in individual recognition, which would suggest the presence of plumage markings visible under UV radiation. Between 1 and 22 d of age, the plumage of 17 male turkey poults (BIG6) was examined. When viewed under a conventional fluorescent white luminaire (which emits minimal UV) the birds were a uniform yellow or white according to the stage of feather emergence. However, when viewed under a lamp emitting radiation with peaks in the UV spectrum, distinct fluorescent and non-fluorescent patches were observable on several parts of the body including the wings, tail, shoulders, thighs, neck, breast and dorsal surface. This paper describes the changes in incidence, size, location and qualitative aspects of these UV-visible markings. The age at which UV-visible markings were first observed on the wings and tail corresponded closely with the age at which injuries to these sites were first caused by pecking, as reported previously. It is suggested that the 'unnatural' appearance of these markings under conventional lighting, which emits minimal UV radiation, might attract or protract injurious pecking from conspecifics.