I heard the thin ascending call long before I could find the bird. I was walking around Bareis Preserve, an overgrown meadow along Walnut Creek in Canal Winchester, and heard the rising ‘ zee zee zee zee zee zee zee zee zee’. Tthe distinctive call hit me like a slap: Prairie Warbler, and it wasn’t really supposed to be there. But is there anywhere where a Prairie Warbler is supposed to be?
Prairie Warblers are the vagrants of the warbler world, seemingly shifting nest areas on a whim. Just days before, I had led a field trip to Clear Creek, where they supposedly nest, and found none. We even walked the Prairie Warbler Trail, near Barneby Center, and came up empty. Something about the habitat there had changed, and the warblers had decamped to other parts of the park. The fussiness about nesting habitat is a feature of this species, as outlined in Val Nolan’s great monograph, The Prairie Warbler. They need meadows with small trees starting to take over, preferably pines or cedars, but other species will do, and the trees need to be spaced apart and a certain height. Only a handful of spots meet their criteria, and those spots might only stay that way for a few years time.
If this focus on nesting habitat sounds familiar, think of a rare little warbler from Michigan. Yes, Kirtlands and Prairies share lots of similarities, in both their appearance and their nesting habitat. But Kirtlands have made the ultimate narrowing, focusing on one type of tree, Jack Pines, which has really restricted their habitat choices. There are still a lot of Jack Pines in Michigan and Wisconsin, and the bird’s population has slowly been increasing and spreading into neighboring areas, but it’s been a painfully slow process.
Lucky for Prairie warblers, they aren’t quite that specific in nest site selection. They prefer small pines, but lots of different trees will do. I’ve seen them in longleaf pine glades in Florida or the pine barrens of New Jersey and New York. They will also utilize cedar glades or deciduous successional fields, and a famous subpopulation in Florida has even adapted to stunted mangrove flats. Some of my fondest birding memories growing up in Miami were searching for nesting Prairies in mangroves, one of the few nesting warblers in the hot south Florida summer.
Here in Ohio, our nesting Prairies seem to accept overgrown meadows or fields of a wide variety. The nesting meadows I’ve seen in the Hocking Hills often had a few Virginia Pines, but sometimes not. Increasingly, though, I’ve seen prospective nesting birds in successional areas closer to Columbus. One year, a bird was at a field in Alum Creek Lake State Park, where many old farm fields have been growing in since the park was set up back in the 1970s. Other’s like the bird at Bareis, have popped up along the network of streamside parks in Columbus, where the Greenways project has allowed succession to start on a lot of old farm fields there as well. These areas may just be reaching a stage attractive to Prairie Warblers, and we may start seeing attempted nesting in nearby areas. At least for a few years. We just need to start keeping our ears peeled for the distinctive song.