Although plumage color aberrations are common in birds, they often are difficult or even impossible to properly identify in the field. Even though some of these aberrations are common, including progressive greying, leucism, and albinism, there is confusion among the mechanisms responsible for each of the color aberrations. Other color abnormalities, such as dilution and ino, are found or reported less frequently. The Keel-billed Toucan (Ramphastos sulfuratus; Piciformes: Ramphastidae) is predominantly black, red under the tail coverts, and the feathers above the tail that are white colored. It has a yellow bib covering the throat and chest with a red band countering it, and the skin of the face is chartreuse. The Keel-billed Toucan is most notable for its massive, multicolored bill that makes up to a third of its length. Here we report a genetic-based melanin deficiency producing an unusual coloration in the Keel-billed Toucan. An individual observed at Pital, San Carlos, in the lowlands of northern Costa Rica in October, 2020 lacked melanin, but retained carotenoids. As most parts of the plumage normally have both melanin and carotenoids, the yellow becomes visible where the black is now absent, such as the ventral feathers. We discuss possible explanations for this unusual coloration.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 51 • No. 2