The black-billed bird at the top, left exhibits the typical adult appearance. The yellow-billed bird at the right is an immature bird, the main differences being that his bill is yellow and the ring around his pupil -- his "orbital ring" -- is yellowish, instead of black as with the adult. The inset at the lower left shows another immature Yucatan Jay, but younger than the first one, with yellow beak and white head and lower parts. The yellow beaks of young birds become black by their third winter. Howell in A Guide to The Birds of Mexico and Northern Central America reports the mostly white plumage as seen only from July through September, so I was lucky to capture it.

— extract from Jim's newsletter