Functional significance of ultraviolet feeding cues in wild turkeys

article i nfo Most birds are able to sense ultraviolet (UV) visual signals. Ultraviolet wavelengths are used for plumage signal- ing and sexual selection among birds. The aim of our study was to determine if UV cues are also used for the pro- cess of food selection in wild turkeys (Meleagris gallopavo). We used avoidance conditioning to test the hypothesis that UV feeding cues can be used functionally for foraging behavior in wild turkeys. Female turkeys exhibited no avoidance of untreated food and 75-98% avoidance of food treated with an UV-absorbent, postingestive repellent (0.5-4% anthraquinone; wt./wt.) during repellent exposure. Male turkeys exhibited 78-99% avoidance of food treated with 0.5-4% anthraquinone. Female and male turkeys that consumed more than 200 mg and 100 mg of anthraquinone, respectively, subsequently avoided food treated only with an UV- absorbent cue. In contrast, unconditioned females consumed 58% more food treated with the UV-absorbent cue than untreated food. Thus, wild turkeys do not prefer foods associated with UV wavelengths regardless of feeding experience. Wealso observed 1) a weak negative correlation between body condition and intestinal par- asite infection and 2) moderate,positive correlations betweenconsumption of food treatedwith the conditioned UV cue and intestinal parasite infection among male turkeys. The UV feeding cue was used to maintain food avoidance during the four days subsequent to postingestive conditioning. Moreover, the consequences of con- suming food treated with the postingestive, UV-absorbent repellent were necessary for conditioned avoidance of the UV-absorbent cue. These findings suggest functional significance of UV feeding cues for avian foraging be- havior,the implicationsof which will enablesubsequentinvestigationsregarding thesensory physiologyand be- havioral ecology of wild birds.