Thursday, September 8, 2011
Vireotown
We have three species of vireos that nest on our farm here in southeastern Ohio: red-eyed, white-eyed, and yellow-throated. There are three others that we see each spring and fall, just passin' through: blue-headed (formerly solitary and I can't seem to remember to use the "new" name), warbling, and Philadelphia. If we really stretched our birding fantasy list to the extreme I suppose we could one day see a Bell's vireo here at Indigo Hill, but if we do, that sighting will get its very own blog post.
All summer long we hear the red-eyeds singing almost constantly. Yellow-throateds seem to be more selective singers, but when they do sing, they do it a lot. Their hoarse-sounding question-and-answer song seems to come mostly from our oak woods.
White-eyeds sing a ton during courtship, then not at all during nesting it seems. I wonder if the tree-top-loving red-eyeds and yellow-throateds sing more regularly (or the white-eyeds less) due to their relative exposure to predators. A red-eyed vireo singing in the top of a tulip poplar is very hard to find. A white-eyed may be skulking in the shadows, but it's usually at eye level or below in a patch of brushy habitat. Does this make them more susceptible to predators?
Now that fall migration has started, these vireos can still be heard singing, though with nowhere near the intensity of the earlier seasons. The other notable behavior of fall migration is the aggressiveness of the red-eyed vireos. They zip and swoop from tree to tree, often chasing other birds. I imagine these other birds thinking "What the heck? Leave me alone!" I'm sure this behavior has something to do with the fluctuation in hormone levels brought on by the end of the breeding season and the onset of fall migration.
The red-eyeds remind me of teenage boys who, when they find themselves just standing around doing, nothing get the sudden urge to punch a nearby shoulder. This punch often elicits another, and so on.
Our vireos' aggressiveness sometimes pays nice dividends, like this morning when a pair of (probably young) red-eyeds chased two warblers out of deep cover in our sycamore tree: one was an adult male black-throated blue (my favorite North American warbler) and the other was a yellow-throated warbler—both firsts for this fall.
Later in September we start sorting through the vireos more carefully, looking for a Philadelphia vireo. We see far more of them in fall than in spring migration. It's one of the many treats of autumn that makes the leaving of summer just a little easier to take here in Vireotown.