Hummingbird at Jewelweed.Courtesy of Rick Remington 

One does not have to be an early-birder to see ruby-throated hummingbirds on the move, flying south to their wintering grounds on the western coast of the Gulf of Mexico, in Mexico itself, and in Central America.

In early August, these aerial acrobats, traveling alone, begin to pass through Evanston and fuel their migration. Wherever there is nectar, be it from a hummingbird feeder loaded with fresh sugar water or a patch of red monarda or orange jewelweed plants with fresh blooms, these birds typically stop to refuel around mid-day.

According to Cornell Birds of North America, fall migration seems to coincide with the peak flowering of the jewelweed, and red tubular flowers may have coevolved with hummingbirds.

If I eat a late lunch on my screened porch overlooking my back-yard garden, I can watch hummingbirds visit two patches of monarda, also known as bee-balm or bergamot, a member of the mint family. The Missouri Botanic Garden has this to say about Monarda didyma: “tubular, two-lipped, bright scarlet-red flowers crowded into dense, globular, terminal flowerheads (to 3 or 4 inches across) somewhat resembling unkempt mop-heads.” In other words, it has lots of individual flowers to visit for that essential nectar.

I prefer to provide natural food sources to sustain migrating hummingbirds. That monarda plants are pretty, require no care, attract and nourish bees, attract the insects hummingbirds need to eat along with the nectar, and bloom for at least eight summer weeks are plusses. It helps to pick blossoms and deadhead those that have finished blooming in order to provide fresh blossoms and prolong the blooming period.

A hummingbird is apt to zoom straight down to its target monarda, where it inserts its tongue into each blossom, sometimes moving clockwise from flower to flower and then from one stalk to another until it has visited every one. Then it is up and off to another location in an instant, only to reappear for another dive down to the next patch of monarda.  

The agility and speed of a hummingbird is nothing short of awe-inspiring. The dives I witness can reach up to 60 miles per hour. As they draw in nectar on the wing, hovering with as many as 55 wingbeats per second, they look like large insects. In fact, their flight resembles that of insects more than that of other birds.

Both male and female hummingbirds are green all over except for white on their chests and bellies. Sexes are distinguished by their throats, white in the female (and juveniles) and ruby red on the male. Females are larger than males, if the term “large” can be applied to a hummingbird.

An adult female weighs in at about 3.5 to 4.5 grams, the male about 2.5 to 3.5 grams (2.5 grams is 0.09 ounces).

To put this in perspective, a nickel weighs as much as two male hummingbirds. I am seeing all females or possibly juveniles hatched this year. No ruby throats on the birds. Males migrate earlier – perhaps I have just missed them.

What are they doing hovering at the monarda and at the jewel weed in Perkins Woods or even capturing insects on the wing?  What does it take to sustain these tiny jewels for their long voyage south?

During the breeding season, ruby-throated hummingbirds will eat half their weight each day. Contrary to appearance, hummingbirds don’t sip nectar as if through a straw. They lick the nectar with their long, fringed and forked tongues, and capillary action along their tongue delivers the nectar to their throats.

On their way to the Gulf, they are probably just tanking up enough to make it to the next refueling stop, using the sugary nectar for the energy to catch protein-rich insects.  

As they approach the Gulf, preparing to cross the 525 watery miles to the Yucatan peninsula, or to fly the coastal route along the Gulf, they go into a stage scientists call “hyperphagia,” a sort of feeding frenzy, during which they double their daily food intake, consuming the equivalent of their total body weight by tanking up on nectar and insects.

They are storing up fat, a necessity to sustain the long-distance haul over or around the Gulf. The energy-rich yellow fat that hummers obtain from their pre-migration pig-out is stored in pockets in the wishbone area, along the flanks, and where legs attach to the body, spreading the weight around. Burning fat provides more energy than burning carbohydrates or protein and also provides water, preventing dehydration during long flights.

These tiny birds have a long way to go. Whatever their route, they may be buffeted by strong headwinds and possibly hurricanes in or along the Gulf. If they have not gained enough weight, they may be too weak to survive. Then, once they arrive in the Yucatan, they must have enough fuel left to sustain them until they find flowering plants in their winter habitat.

Habitats that provide nectar sources are essential all along their perilous voyage. While our influence may be limited in Central America, residents here can help prepare these amazing tiny birds as they undertake their long journey south by providing nectar stations either in feeders or by planting an array of flowers including monarda, trumpet creeper, cardinal flower, royal and round-leaved catchfly and fire pinks.

We can enjoy watching these amazing birds and helping them along their way as we enjoy our beautiful, sustaining gardens.

Libby Hill

Libby Hill is the author of "The Chicago River: a Natural and Unnatural History. She has been writing about birds and trees and Evanston's natural history for the Roundtable since 2004.