“Citron-crested Cockatoo”

Cf. Yellow-crested Cockatoo.  “Citron-crested” and typical Yellow-crested Cockatoos are closely related forms that inhabit adjacent islands in the Lesser Sundas.  They are approximately the same size and overall coloration, with the only consistent difference being the coloration of the crest: yellow versus pale apricot-orange.

They do not occur together naturally, but because both are popular cagebirds both can occur anywhere (climate permitting).  There are no known introduced populations of “Citron-crested”, but one or more individuals may have appeared around Singapore (though these individuals could possibly be hybrids of Yellow-crested with another species such as Salmon-crested—see Additional Photos below).

According to the initial study of populations traditionally classified as Yellow-crested, “Citron-crested” has comparatively long wings, tail, and crest feathers.  However, an isolated Yellow-crested subspecies, abbotti, exceeds it in all of these measurements.  “Citron-crested” appears to have a larger, deeper-based bill than most Yellow-crested, but a different subspecies, sulphurea, has a similar-sized bill.  Based on publicly available recordings, it appears that “Citron-crested” may have a deeper, mellower voice.