Saturday, August 18, 2018

The Migrants are Starting to Arrive: Pacific-Slope Flycatcher on the Tuolumne River


Sometimes I'm just really lucky. I'm no expert, not by a longshot, and though I can recognize most of the common species in our area, I'm at a loss when some of the rarer migrants come through. I learn most by repetition, and if I've seen a bird only once or twice previously, I won't be able to pick it out readily. I have to get pictures and pull out the field guides.

That's what happened yesterday. I was keeping a careful eye out for Buntings and Grosbeaks, my most exciting recent discoveries, when another bird landed in the branches in front of me long enough for two quick shots. The distinctive shape of the eye-ring and the bi-colored bill nailed it: a Pacific-slope Flycatcher (Empidonax difficilis). I've only seen it once before, during the spring migration.

Pacific-slope Flycatcher might seem a slightly clumsy name, but how about Cordilleran Flycatcher? Those are fairly modern terms for a bird that was first described in 1858. Until 1989 the two species were considered to be one: the Western Flycatcher, a more normal-sounding name. The problem is that the species split was based on vocalizations and breeding habits, and in practice the birds are very difficult to tell apart from each other. Some sources on the web suggest that the species split was premature.

In any case, I was lucky to identify this bird as a flycatcher, period. But I was really happy to get a fairly sharp picture (compare it to my last image here), and maybe next time I'll recognize it on sight!.

No comments:

Post a Comment