As we all know, only the ASY or After Second Year Purple Martin bears the all over steely blue coloration. It always makes me wonder exactly why they called them "Purple" in the first place. It drives me crazy as an artist. If I paint them blue people will say, "That ain't no PurpleMartin-It's BLUE!" But if I paint them purple others will say, "It aint no Purple Martin, cause they are blue!" So the insecure person in me wants to please. What can I say... ANYWAY!!! All other purple martins are frustratingly similar to the untrained eye. Don't fret. I will give you some tips.
Take the SY purple martin male, for example. He has survived only 1 migration and this is his first trip back to the colony since he was born. He has undergone 1 molt in Brazil and he returns with some of the purple/blue feathers but will not be considered a true adult until his second trip back. He has a mottled appearance and ranges from only a few purple/blue breast feathers to large blotches. He is often confused with females which also have the brown/grey breast, belly and undertail coverts, or as the area is called the crissum. Remember that name, crissum, there will be a test.
ASY and SY Females
Ages in Purple Martin females is agonizing for me and without a good look at that undertail area or crissum, you can be hard-pressed to tell the difference in ages. The younger, SY, birds will tend to be a brown color above. The ASY females will have more of that steely blue color on the shoulders, top of the head and back. Underneath on the breast will be the brownish/grey. Under the tail (below the vent) in the area called the crissum is the real difference. The color will sometimes make the feathers look like scales.
First look at a ASY female:
Notice that scale look on her undertail coverts (crissum)? That is tell tale of an older purple martin female.
Now look at a SY female:
See how her crissum is almost devoid of all dark color? She looks a creamy white underneath. She will tend to be that brownish color over more of her body than the ASY females also.
So there you have it. In a nutshell age ID of Purple Martins.
Copyrighted 2009: S.Halpin/ www.PurpleMartins-R-Us.com