Fading of numbers from patagial tags: A potential problem for long-term studies of vultures

New World vultures cannot be banded with conventional leg bands. As a resul t, commercially available cattle eartags are commonly used to mark individu als in field studies. Although there is no evidence of numbers fading from these tags when they are used to mark cattle, I recorded at least four case s (3.8% of marked birds, 25% of resighted birds) in which tags became parti ally or completely illegible less than 3 yr after being used to mark Turkey Vultures (Cathartes aura). Because tag fading could adversely affect long- term studies of vultures, workers should be aware of this potential problem so that appropriate precautions can be taken.