Fat quill secretion in pigeons: could it function as a cosmetic?

Abstract

In order to maintain functionality of the plumage, birds apply a variety of fatty substances to the feathers, usually derived from the preen gland. Such secretions could also have cosmetic functions, altering plumage refl ectance, and there is indeed some evidence for such cosmetic functions of preen fats. Some birds, noticeably pigeons, use fats derived from modifi ed feathers, so called fat quills, in a presumably similar fashion, but almost nothing is known about their putative functions. Here we present a fi rst test of the possibility that fat quill secretion could function as a cosmetic. As models we used domestic pigeon races that produce fat quills, we fi rst confi rm their extensive use in plumage maintenance behaviour. We then assessed the eff ect of experimental addition and removal fat quill secretion on refl ectance of white feathers using refl ectance spectrometry and physiological models of avian colour vision. Addition of secretion to cleaned white feathers resulted in a signifi cant, discriminable change in the feather refl ectance spectrum, which was strikingly similar to the absorbance spectrum of passerine preen gland secretion. However, like previous studies on preen gland secretion, removal of fats from intact feathers did not signifi cantly alter feather refl ectance, indicating that fat quill secretion when present in quantities as applied by the birds does not noticeably aff ect plumage refl ectance. Th erefore we conclude that the potential for the fat quill secretion to modify plumage colour appears limited at best, and other functions, such as antibiotic defense against feather-degrading bacteria, should be considered. © Koninklijke Brill NV, Leiden, 2010.

Feather function and the evolution of birds

“…In addition to feathers being ground physically into a cosmetic through structural degradation, modified pulviplume feathers (Peters, Delhey & Klonczinski, 2010) or apteria (Menon & Menon, 2000) can also secrete lipoid fat (Peters et al ., 2010), which is used as cosmetic coloration through direct application to feathers, or by mixing with pulviplume powders. Lipoids mixed with pulviplume powders typically produce a yellow or orange colour, staining white feathers when applied topically by the bird.…”

On the Multifunctionality of Feathers and the Evolution of BIrds

“…In addition to feathers being ground physically into a cosmetic through structural degradation, modified pulviplume feathers (Peters et al 2010) or apteria (Menon and Menon 200) can also secret lipoid fat (Peters et al 2010), which can also used as cosmetic coloration through direct application to feathers, or by mixing with pulviplume powders. Lipoids mixed with pulviplume powders typically produce a yellow or orange color, which would stain white feathers when applied topically by the bird.…”