Date: 11/15/18 10:51 am From: Derb Carter <derbc...> Subject: Cullowhee martin
I have a fair amount of experience with all the Progne martins in the Americas, except Galapagos. I think the bird found, photographed, and posted in the CBC gallery is almost certainly either a Cuban, Caribbean, or Sinaloa Martin, any of which would be an extraordinary record. Female plumages of these species are very similar. My limited experience with Sinaloa was years ago when it was considered a subspecies of Purple. Sinaloa is quite rare within its range in western Mexico, which is much more remote from western NC. It is smaller than the other two. This is imprecise from the photos, but my estimate of the wing chord in the specimen is 142-143 mm which is outside the reported range for Sinaloa of 136-138 mm, and within the range 134-149 and close to the mean 143.5 of Caribbean (I could not find measurements for Cuban).
I compared the posted photos to some photos I took of Cuban Martins on recent trips and it is generally identical to some in the photos. This does not, however, eliminate Caribbean because in female plumage it is essentially identical to Cuban (male Caribbeans are white below; male Cubans solid blue/purple). I checked some references that say the white below is more restricted on Caribbean than on Cuban, but in looking at photos of both species I really see little difference. One thing I did notice in photos of each species is the undertail covert of female Caribbean is always pure white, while the undertail covert of many but not all Cuban seems to have a few dark feathers. I have not seen this mentioned in guides. The Cullowhee bird has a pure white undertail.
Hopefully further investigation will reveal the identification, but my guess from the photos is either Caribbean or Cuban.