Bird Odors and Other Chemical Substances: A Defense Mechanism or Overlooked Mode of Intraspecific Communication?

Bi ds e i an chemical compounds, though ornithologists rarely consider them.Avian odors, for example, are readily detectable to humans in at least 17 avian orders and 80 genera (Table 1; data from Weldon and Rappole 1997).Scents consist of volatile chemicals, and birds embrace a remarkable diversity of aromas, such as the musky plumage of storm-petrels (Hydrobatidae; Jacob and Zisweiler 1982); the tangerine-like perfume of Crested Auklets (Aethia cristatella; Humphrey and Phillips 1958); the acrid, sour odor of Hooded Pitohuis (Pitohui dichrous) and Variable Pitohuis (P.kirkocephalus; Dumbacher et al. 1992); the sweet and dusty fragrance of the Kakapo (Strigops habroptilus; Butler 1989, J. C. Hagelin pers.obs.); and the foul stench of the Hoatzin (Opisthocomus hoatzin; see Weldon and Rappole 1997).Birds also produce a variety of substances consisting of larger, less volatile compounds.Frequently odorless, these occur in various forms, such as saturated fatt y acids of uropygial gland secretions (Jacob and Zisweiler 1982, Sweeney et al. 2004) ) or toxins sequestered in plumage or skin (e.g., Dumbacher et al. 1992).