Green’s Dictionary of Slang

parakeet n.

[their stereotyped noisiness and love of bright colours; note WWI Aus. milit. parakeet, ‘Staff Officer [...] So called from the red gorget tabs and the red band around the hat of a Staff Officer’ (Pretty, Glossary Of Slang [...] in the A.I.F., 1924)]

(US) a Puerto Rican.

[US]D. Claerbaut Black Jargon in White America 74: parakeet n. a Puerto Rican.