A feeding frenzy is developing at my hummingbird feeders. While I have been hosting ruby-throated hummingbirds since the first one appeared on May 4th, summer numbers have been limited to a pair or two of adults, and then their young. For the last week or so, the number of birds present has been rising. This suggests that the species’ movement south has begun. Ruby-throated hummingbirds’ breeding range extends north to the mid-latitudes of the Canadian provinces, and it is these birds (typically the males first) who are beginning their retreat south. Photoperiod, or length of daylight, seems to be the primary trigger for migration. An interesting study in 1982 suggested that the timing of eastern hummingbird migration matches the flowering (and nectar production) of jewelweed. Is this a case of impatiens for impatient males? Jewelweed or not, the feeders are much busier today.
The activity brings to mind one of the reasons why I am so passionate about my hobby. I am always intrigued to understand the story behind what I observe in my yard. Seeing something new or someone different at the feeders propels me to my library of bird books, or to the internet, to learn more. And the influx of hummingbirds to my feeders speaks to one of the most amazing stories in the avian world: migration. Billions of birds of all descriptions move over the face of the earth twice a year following the changing seasons. I have recently concluded reading a book by Scott Weidensal entitled, “Living on the Wind: Across the Hemisphere With Migratory Birds.” Add it to your winter reading list. I highly recommend it.
Ruby-throated hummingbirds winter in Central America and make a trans-Gulf of Mexico flight twice a year. This is a creature that has less mass than a nickel in your pocket yet is able to fly non-stop across 700 miles of open water! And hummingbirds are a good example of a species that demonstrates “site fidelity,” they return to the same location each breeding season. A few years ago, I found an early male hovering in the exact spot where I had a feeder the prior year. The only evidence that this location on my porch had once been a food source was a small cup hook in the ceiling. Yet he was looking for nectar at that exact spot, proving to me that after months of time and thousands of miles, this was last year’s bird back on my property! As you might guess, the feeder was back up within minutes!
Science is only just beginning to understand how birds navigate during these annual travels. Some of the theories include: they can sense the Earth’s magnetic field, they use visual cues of landforms below, they use celestial bodies as a compass, they learn the route from their parents, or some combination of the above. With the recent miniaturization of electronics, tracking birds across the globe has become possible. The study of avian migration is cutting edge science and our knowledge of this amazing feat is presently exploding.
Some folks take their nectar feeders down early, fearing that the hummingbirds will not migrate while food is present. This is simply not true. The innate impulse to migrate is much stronger than that. It is far better to offer a source of sustenance to hummingbirds along the path of their arduous journey. As this mass movement of hummingbirds plays out, my feeders will remain open for business, both for my “homies” as well as those transients passing through. In fact, I keep nectar feeders out until I risk having the nectar freeze overnight. Autumn represents the best chance for vagrants: unexpected visitors. Occasionally a few western hummingbird species mistakenly fly west instead of south. Each year there are feeder surprises! Last fall, in my home state of Pennsylvania, both Anna’s and Rufous hummingbirds appeared in backyards. So continue to enjoy these amazing avian wonders and, if you see an odd looking ruby-throat this fall, grab your field guide!