Favoritos de thylacine

Sadly, the Common Tern is now far less common in our area than it once was. I've been living & birding on Vashon for nearly 7 years and this was my first sighting of this species. Observed foraging over the water and also on an exposed sand bar, resting adjacent to a Caspian Tern, which provided a wonderful comparison opportunity for myself, as well as everyone else attending the community bird walk I happened to be co-leading at the time. I can only hope it will not be another 7 years before I get the chance to see this delightful tern again.

(A very special "thank you" to V for letting me use her cellphone to take these pics through the scope. I was kicking myself for not having brought my camera and I am extremely grateful to have these record shots.)

In sagebrush country
Very short tail that doesn't fit any Microtus sp., nor Clethrionomys gapperi.
The only other vole looking similar is Phenacomys intermedius but the range and habitat is wrong for it.
Am I overlooking something? Any suggestions are welcome.