Thanks to a cold winter and a cool spring, the foliage remains behind schedule in the American Heartland. In concert, some of our summer birds have been slow to return.
Just yesterday, I encountered the first ruby-throated hummingbird and great crested flycatcher of the season. Of even more significance, I have yet to see a chimney swift; flocks of those aerial insectivores are usually strafing the evening sky by mid April.
Our warming climate appears to be responsible for the sluggish spring. Though one might expect the season to unfold even earlier, the energized jet stream, always unsettled in spring, has produced broad atmospheric troughs across the country, allowing cool, Canadian air to reach more southern latitudes. Triggering severe storms throughout the spring, these chilly incursions have also slowed the seasonal transition that we have come to expect.
