Return of the Prairie?

Here's a nice find from this morning, first located by a friend of mine:

Prairie Warbler (Setophaga discolor), Grant Woods FP, Lake Co, IL  6/27/2014

This is a male Prairie Warbler (Setophaga discolor), and he's only the third one I've ever run across in the county. The first one, in fact, I never did manage to see. Thankfully, they have a very distinctive voice -- a slightly buzzy, very musical series of notes running up the scale. Their song always reminds me of Arethra Franklin trying to sing a Northern Parula ditty.

They breed in early-successional shrublands, which are in rather short supply in this area these days. Back in the 70's, though, they bred in Illinois Beach State Park. That habitat hasn't changed much over the years, and I don't know why they disappeared.

I mentioned that this was the third one I've found here? The first two were last year in May. Given that this guy's been singing away for at least two weeks, and he was joined by a second male, I have to wonder if this is a signal of a range expansion back into the county. In the case of this particular male, it's likely to be an unsuccessful one, since he's still singing his heart out at the end of June. (Typically, a male that's found a mate will spend a lot less time singing by now, since there's no longer any need to attract a female.) But that's the way that ranges grow -- the first few birds into a new area will probably not succeed. Once a couple of birds have found mates, and we have a few nestlings who have grown up here, then the next birds to wander into the area will see a reason to stay, and we have a new expected species.

Evolution can be seen as an exploration of the incredibly large universe of possible genetic programs, set against a wildly varying environment of constraints. An occasional individual wanders into new territory, and if it's really lucky, an entire population will someday follow it. But that's an abstract way to view things. Genetic programs only evolve when they're in a body that can actually do things, and in this case, we're seeing the abstract concept of exploration playing out in very concrete, and very musical, little warblers.