The Estevan Rusty Blackbird
- Alvaro Jaramillo who has written the Helm's Guide "New World Blackbirds and Icterids" suggests that the Estevan bird is a Rusty Blackbird in very worn plumage. This explains why the bird was so confusing to me because its plumage was not typical for this season.
If I understand correctly, the typical fall fresh rusty colourful non-breeding plumage transforms into the pristine black breeding plumage through the process of feather wear. Sibley's Guide suggests that the non-breeding rusty tinged plumage is typically held until March.
The logic then is for some reason this bird's plumage is already worn to the point that the diagnostic winter rusty wing (tertial and secondary) feathers and some others now are as dark as breeding plumage as early as the last week in November and early into December.
I was unaware that this was possible; however, I know that birds are simultaneously a species and are individuals. References to typical plumage changes are no doubt only general guidelines and not absolute. No guide will contain all the possible variations, unfortunately.
There are other differences some of which are subtle between Rusty and Brewer's Blackbirds such as the facial pattern and the shape of the bill. If you check the facial pattern of Sibley's Drab 1st winter male and the basic plumaged Rusty Blackbird these differences are not as great as one would image in my opinion.
There is always much to learn for the inquisitive mind.
[Non-text portions of this message have been removed]