Among the 20 or so races of peregrine worldwide, the tundra peregrine (Falco peregrinus tundrius) was the last to be officially recognized by ornithologists.
Professor Clayton White, now retired from BYU, first described it in his Ph. D. dissertation back around 1968.
The other "tundra" peregrine (F.p. calidus), occurs in Eurasia, and to my knowledge, has never been confirmed in Washington.
Trying to call the subspecies of individual peregrines in WA is always fun but is far more difficult and challenging than you might have been lead to believe.
Certainly there are some individual birds that can be assigned a subspecific identity. Obviously all eastern Washington and some western WA breeding pairs are anatums (F.p. anatum). Many of our coastal pairs are classic Peale's peregrines (F.p. pealei), so both of these resident subspecies are known to breed here. The tundra peregrine does not.
However, it does migrate through WA during both spring and fall. Several banded migrant tundra falcons from AK have been recovered in WA on migration.
For example, the first ever WA peregrine band recovery, a nestling banded on the Colville River in AK in the 1950s by none other than the late Tom Cade, was beaten to death by a logger during fall, as it sat on a Snow Goose it had just killed.
Times were different back then.
During our winter months, most peregrine experts are quite hesitant to positively call subspecies of both adults and juveniles. You probably should be too.
Here is the problem with identifying tundra peregrines in the field.
First off, with few exceptions, the vast majority are wintering in Central and South America. They are the most highly migratory peregrine in the world and are outdone among all falcons only by the Amur Falcon (Falco amurensis) in total distances traveled.
Second, most birders, having rightfully looked at the paintings/photos of juvenile peregrines in the field guides, learn that a light head, light supercilium line and white auricular, always indicate a tundra peregrine. They often do. But it is more complicated than that.
Anatum peregrines and, surprisingly, many Peales Falcons can also show these same features.
Clayton White pointed out early on that approximately 25% of Queen Charlotte Island Peales juveniles had light heads and superciliums that were similar to tundra peregrines.
Clayton and Steve Herman, both peregrine experts, were the first people to mentor me into always using caution about calling peregrine subspecies in the field. Good advice.
Subsequently, among the several hundred WA nestling peregrines that Ed Deal, Martin Muller and I have banded over the many years in the San Juan Islands, Seattle and Tacoma, several of these known origin, color-banded birds have exhibited these features, incuding the supercilium line and light head.
I have seen young birds hatched in downtown Seattle that many inexperienced birders would definitely call tundra peregrines.
A good friend prompted me to address this issue because of the recent Fir Island reports of a juvenile tundra falcon. In looking at several photos of this bird, I can understand the inclination to ID it as such but I think Ryan is correct in classifying it as unconfirmed.
So, go have fun, challenge yourselves, and keep learning but in my opinion, it is probably best to not positively call peregrine subspecies in winter unless you can read a band on the bird and positively know its natal origin.