This morning the blue-headed vireos were vigorously defending their territory from a blue jay. Though it was much higher up in the trees than their nest, the pair was scolding and dive-bombing the jay, hoping to drive it off.
Unfortunately they may be protecting a young cowbird. The noise overhead roused a hungry nestling, just one, its eyes still closed. It seems too large already. Cowbird nestlings eject their nestmates, so seeing just one head is a bad sign. I checked the ground beneath the nest for evidence and found nothing, but such a morsel probably would have been found by a possum or raccoon on its nightly prowl. I fear my guests may be raising a chick that is not their own.