Good Natured: Hummingbirds
We have a few birds in our area that even nonbirders consider unmistakable. Most folks, even if they're relatively new to the area, can recognize an American robin; I'd wager they could also identify our state bird, the northern cardinal, either the crimson male or the tawny female. Or both!
And then we have hummingbirds. Is there anything else in the bird world like them? (Note that we said bird world. We're going to leave hummingbird moths for another time.)
Itsy bitsy and flitty, with iridescent plumage that flashes emerald in the sun, hummingbirds shine like winged jewels among our local feathered friends . As a hummer darts from flower to flower we can't help but admire how its bill, shaped like a drinking straw, is so exquisitely adapted for extracting sweet liquid from flower nectaries.
Ah, but make no mistake, that bill can do way more than sip nectar. As improbable as it may seem, hummingbirds also use their tiny tube-shaped mandibles like tweezers, plucking insects not only from flowers but also, amazingly enough, from mid air.
I remember walking along the Batavia Riverwalk one fine summer evening s few years ago. The weather was warm and insects were in abundance—especially the tiny gnats that form mating swarms above and around waterways like the Fox River.
I'd stopped on the west side of that looped pathway, to pick a gnat from my teeth, if I recall correctly, when I noticed what appeared to be a large insect feeding on those same protein-packed winged morsels. I squinted against the sun to try and discern any details while my mind reeled through the list of local insects that capture prey on the wing:
Green darner dragonfly
Twelve-spotted skimmer dragonfly
Blue dasher dragonfly
Dragonfly, dragonfly, dragonfly…I was going nowhere fast! Meanwhile, the airborne creature was zipping back and forth, catching its fill. It appeared to be using the tip of a branch as a home base of sorts, from which it would launch into the air and then return. Its movements reminded me of a helicopter in flight.
Helicopter, helicopter, helicopter…Ding! That pattern of flight combined with that tiny body could mean only one thing (and I'll bet you've guessed it by now): Hummingbird!Back home that evening, I was eager to learn more about this “new" behavior I'd witnessed. It turns out, it was “old" news…by more than 200 years!
One of our country's first ornithologists, Alexander Wilson, wrote in the early 1800s,"I have seen the humming bird, for half an hour at a time, darting at those little groups of insects that dance in the air in a fine summer evening, retiring to an adjoining twig to rest, and renewing the attack with a dexterity that sets all our other flycatchers at defiance."
Moving ahead 150 years, to the research of ornithologist F. Gary Stiles, I learned that the foraging pattern of taking off from a branch, grabbing an insect and alighting back at the same spot actually has a name. Stiles dubbed it sally hawking, one of four distinct insect-hunting behaviors he observed among the Costa Rican hummingbirds he studied.
In case you're curious—and I'll bet you are—the other three are:
Sally gleaning, where the bird flies from a perch to a leaf, picks off an insect, and returns to its perch
Hover hawking, where the bird flies amid a cloud of insects, consuming many as it makes its way along
Hover gleaning, where the bird uses its tongue to extract insect(s) and spider(s) from a stationary source like a flower, leaf or spider web
Pretty neat, huh? But the really interesting information on hummingbird's feeding habits comes courtesy of Doug Tallamy, an entomologist at the University of Delaware and author of several popular books on the relationships between native plant and insect communities. Prof. Tallamy estimates that 80% of a hummingbird's diet is insects and spiders.
Eighty percent! Holy cow! Granted there will be seasonal variations, and differences between species. But the fact remains, insect proteins and fats are essential to hummingbird survival.
Here in northern Illinois, our predominate species is the ruby-throated hummingbird. It's widely recognized, even by non-birders, and is widely welcomed into yards with nectar feeders of all shapes and sizes. I picture these little birds gobbling arthropods by the 100s, then washing them down with sweet carbohydrates—sugary fluids that also are important but play a lesser role than a lot of us thought.
Next week: We dive deeper into hummingbird diets and the role humans play in them.
Pam Otto is the outreach ambassador for the St. Charles Park District. She can be reached at potto@stcparks.org.
