A Survey of Birds Odorous or Unpalatable to Humans: Possible Indications of Chemical Defense
We solicited information from field and museum ornithologists on the birds that they consider odorous and/or unpalatable in order to identify species that may use chemicals to deter predators. Ninety-two ornithologists from the Americas and Eastern Europe responded to our survey. Eighty genera and 10 families representing 17 orders, primarily Procellariiformes, Falconiformes, Psittaciformes, Cuculiformes, Piciformes, and Passeriformes, were cited as containing malodorous or uniquely odorous birds. Two orders (Opisthocomiformes and Trogoniformes), five families (Procellariidae, Cuculidae, Bucconidae, Picidae, and Furnriidae), and one subfamily (Drepanidinae) were reported to us as either containing many odorous species or consisting primarily of them. Thirty genera and three families representing 13 orders, primarily Passeriformes, were reported to us as unpalatable. The birds cited in our survey and those previously reported as odorous and/or unpalatable are tabulated. Our survey and review point to a number of taxa that may use chemicals to deter predators, although we acknowledge that compounds imparting aversive or unique odors or flavors may arise for a variety of reasons, e.g., as dietary by-products.