AUDUBON'S ORIOLE (Icterus graduacauda)

A little help in aging and sexing individuals

Contrary to many field guides and reference sources, I believe it is possible to differentiate adult (after second year) male and female Audubon's Orioles in most instances.  I have assembled some photos and some details to help.  By no means is this a thorough treatment.  Just a helpful primer for now.  Maybe if I can find time and motivation it can evolve into an article.  Of the references on Audubon's Orioles out there, New World Blackbirds by Alvaro Jaramillo and Peter Burke is the best.  I highly recommend it if you are interested in Icterids. 

Tail - The undertail is the gold standard in sexing an Audubon's Oriole in definitive basic plumage.  Females usually (always?) have pale markings on the undertail.  Generally R6 (the outermost tail feather which is also the shortest) is the most extensively marked feather.  R6 shows a yellowish tip which usually extends up the feather.  The remaining feathers are similarly marked but it usually becomes less pronounced as you make your way from R6 to R1 (central tail feather).  Below are female and male specimens (all photos are specimens from the Field Museum, Chicago and are only of the audubonii subspecies.) 

Firgure 1.  Female Audubon's Oriole.  This shot shows the variation within females.  Some have extensive pale areas in the undertail while some like the one in the middle have very little and it is mainly restricted to R6.  

Figure 2.  Male Audubon's Oriole.  Most males have whitish looking tips to the tail feathers but these are difficult, or impossible, to see in the field.  All of the above males do have some whitish tips to the tail feathers.  It stands out most on R6 of the first bird.  In the field it is likely that you will just see an all black undertail.

Ventral markings - Less definitive but apparently fairly reliable is the size and raggedness of the breast spot.  Males have breast spots that extend further on the breast and have more pronounced streaks that radiate out from the breast spot.

Figure 3.  Male Audubon's Orioles shown on the top row (last bird is a female) and females on the bottom row.  Notice how strongly marked the males are compared to the females.  You can see that the breast spot extends further onto the breast and is often heavily streaked.  Females have restricted breast spots that are not heavily streaked.  Females can have large breast spots (such as the last bird on the top row) but notice the lack of heavy streaks radiating out from the black area.  Also notice the differences in undertails discussed above.

Dorsal markings - Things to look for on the dorsal side is the overall color of the back and rump, wing and tail color, and the nape where the hood and back meet.  Males are yellow on the back and rump while females are olive.  Wings and tail range from brown to blackish-brown on females and are black on males.  Females have a fairly straight border where the hood and back meet.  Males show a ragged or shaggy appearance where the hood and back meet.

Figure 4.  Females.  Note the olive back and rump and dusky wings and tail.  Notice the clean border where the hood and back meet at the nape. 

Figure 5.  Males.  note the yellow back and rump which is brighter than the females.  Wings and tail are black providing more contrast with the wing edgings. Notice the shaggy/ragged appearance where the hood and back meet.  Males often have black streak bleeding out from the hood onto the back.

Young birds - Juvenile birds do not have a hood (obtained during Baisc I molt).  Juvenile birds and birds in Basic I have yellowish tail feathers (upper and under tail) .  R1 and possible other retrices are molted during Basic I.  The yellowish tail feathers are generally retained until definitive basic molt that takes place in late summer/fall of their second year. 

Figure 6.  Males (3) on the left and females (3) on the right.  Each series are two birds having obtained Basic I plumage  (hood and breast spot present) and one juvenile.  Note the yellow tail feathers of all birds.  I did not spend a lot of time with less than definitive basic specimens so I cannot address sexing issues in Basic I plumage.