ETYMOLOGY
probably from an extended form of cock (a mature male of the domestic chicken) + bird
EXAMPLE
“…The artist’s occupation is gone henceforth, and the painter’s studio, like ‘all charms, must fly, at the mere touch of old philosophy.’ So Major Campbell prepares the charming little cockyoly birds, and I call the sun in to immortalize them. …”
From: Two Years Ago
By Charles Kingsley, 1857
Lexicophilia 