Most Washingtonians will recognize this as the legislative building on the Capitol campus in Olympia, but you might not know that a dozen miles or so southwest of this structure is the Capitol State Forest. The CSF is state-owned forest land, and is extensively logged (with the money providing revenue for our cash-strapped state). Anyone can use the logging roads to drive deep into this commercial forest, as long as you pull to the side when the giant logging trucks comes barreling along. I got up at 4:45am this morning to head to the CSF, in large part because it’s the closest place to my house where one can reliably find nesting Hermit Warblers.
Hermit Warblers are small song birds (ornithologists and birders call song birds ‘passerines’ because they all belong to the same taxonomic order, Passeriformes) which show up in southwest Washington in May and stay until September. They winter in Mexico and points south, attain a maximum length of about 5 inches (including bill and tail), and weigh in at about one-third of an ounce (9 grams for your SI-enthusiastists, or about the weight of 3 pennies). Hermit warblers are partial to mature conifers at middle and upper elevations in the CSF, and spend most of their time singing from the tops of 150-foot fir trees. Needless to say I didn’t get photos with my point & shoot camera, but you can see some awesome Hermit Warbler pics by Robert Royse here.
Hermit Warblers are not that easy to find or see, but after about 45 min in the CSF I tracked one down. Or at least I thought did. But of course, in the CSF, all is not always what it seems. This area southwest of Olympia marks the northern-most breeding range of the Hermit Warbler, which can be found south throughout western Oregon and northwestern California. But it also marks the *southern-most* breeding range of Townsend’s Warbler, the sister species to the Hermit Warbler. Townsend’s Warblers are genetically very closely related to Hermit Warblers, and even look somewhat similar (although they have black on the head and yellow on the breast and belly). You can see some of Royse’s Townsend’s photos here.
Townsend’s Warblers usually breed from northwestern Washington up through BC and into Alaska, but a few stay as far south as the CSF during the nesting season. Now it’s not that hard to tell a Townsend’s from a Hermit – as you can tell if you looked at the photos. The problem is that occasionally a Townsend’s male mistakenly mates with a Hermit female (or vice versa!) in this narrow “zone of overlap,” and produces baby Hermsend’s (or Townmit?) warblers. And these hybrid warblers can be dang tricky to identify, as they can look quite a bit like one or the other parent (or sometimes a bit like a half-and-half mashup of both).
In your 9th grade biology textbook you might have learned that different species cannot successful breed with each other to produce fertile young. That’s true most of the time, but there are a few closely related species of birds that CAN successfully interbreed. Which makes biologists scratch their heads at times wondering what a “species” really is, and how to decide which populations are true species and which are just highly variable subspecies.
Back to my warbler in the CSF – a careful inspection showed that it was (at least to the limits of my observational powers) a pure Hermit – a totally yellow face and no visible yellow below the black bib. I ran into at least 9 Hermit Warblers in a few hours of knocking around the forest, and almost all of them seemed to be lacking visible signs of hybridization (although when they’re playing peek-a-boo 150 feet up offering 1-2 second glimpses, it’s sometimes hard to tell!).
Around lunchtime I headed back down the logging roads and back to the interstate. Passing right by the state capitol, I decided to stop and take a brief tour (the main capitol building is 3 min off the highway!). It’s definitely worth a stop – free tours leave from the second floor every hour on the hour from about 10am to 3pm. And after you tour the capitol, you can zip down to the Capitol State Forest to see a Hermit Warbler (easiest to see May through mid-July along the B- and C- roads near Larch Mtn and Capitol Peak – bring your binoculars!).