[Maine-birds] Summer Tanager -- age & sex of Monhegan bird

It's been great fun to read about and all the good birds on Monhegan. One bird that seems to have caused some confusion is the Summer Tanager. There is no doubt about the species, but some have reported it as an immature male, others a female, and others (safely) not sure which. Prompted by Marie Jordan, I thought this an excellent lesson worth sharing. Cutting to the chase, the bird on Monhegan is an immature female.

Bill Blauvelt and Marie have some fantastic photos of this confiding bird. Bill has a photo that is especially useful for ageing: https://flic.kr/p/sdgsUW
Here one can see the next to innermost secondary (aka tertial) is brownish and worn. On top of it is a smaller, fresh, greenish feather acquired as part of this bird's pre-alternate molt (December to March; finished before northward migration). The brownish older feather and the new, reddish-tinged inner greater coverts (the larger feathers overlying the folded primaries and secondaries) indicate the age of the bird—a first-year immature.

But what about the reddish tinge? Isn't that a male character? Yes and no. Male Summer Tanagers are greenish-olive in fall but acquire new bright red feathers over the winter and early spring (same pre-alternate molt mentioned above from Dec-Mar). When those immature males come north, they show patchy red splotches and, often, an entirely red head. The key is that a male's new red feathers are crisp, bright red like the color of the adult male. The extent of these red feathers is variable, but they always contrast distinctly and usually form larger patches.

Although known for a long time based on specimens, it is still not widely appreciated that female Summer Tanagers--both young and old--can show reddish tinged feathers, especially in the tail coverts and tail. They also can show dull red feathers scattered in their body plumage. There is even one case of an entirely (dull) red female. The Monhegan bird perfectly fits the description of these reddish-tinged females.

Looking at specimens, Ken Parkes found that the reddest (or most "masculine") plumaged females were also those undergoing the most extensive pre-alternate molt, suggesting that hormone levels at the time of feather replacement might influence the amount of red shown. Parkes also showed that both spring immature females as well as adult females can show reddish in the plumage. His short note is here:
https://sora.unm.edu/sites/default/files/journals/wilson/v079n04/p0456-p0458.pdf

Based on birds in the hand, Elizabeth Teulings presented data on several red-plumaged females. Her results from banding are here:
http://www.carolinabirdclub.org/chat/issues/1973/v37n2suta_plumage.pdf

Kudos to Marie Jordan and Joanne Stevens for looking haahd at this.

Louis Bevier
Fairfield

--
Maine birds mailing list
maine-birds@googlegroups.com
http://groups.google.com/group/maine-birds
https://sites.google.com/site/birding207
---
You received this message because you are subscribed to the Google Groups "Maine birds" group.
To unsubscribe from this group and stop receiving emails from it, send an email to maine-birds+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.