Mad About Science: Hummingbirds

By Brenden Bobby
Reader Columnist

Hummingbirds are unique creatures. They are capable of hovering, similar to many winged insects, and they feed from flowers similarly to bees. What you might not realize is that hummingbirds actually eat insects as well. They are very strange and wonderful creatures.

A rufous hummingbird captured in mid-flight. Courtesy photo.

It’s likely that you’ve seen a hummingbird around here, whether you’ve set out a feeder or clocked the distinctive hum of their wings as they zip by. But did you know that there are only three different types of hummingbirds that are known to visit 7B? Hummingbirds experience something called sexual dimorphism, which means that males and females of the same species will look very different from one another — this can make males and females of the same species look completely unrelated to the untrained eye.

Sexual dimorphism is common among avians, particularly in the Western Hemisphere. Numerous South American bird species will have very dull or speckled brown females but very brightly colored males. There is an evolutionary reason for this occurrence. The primary function of the male bird is to attract females and spread its genes through mating. The female birds need to remain camouflaged and relatively stationary for long periods of time to care for their offspring. Being camouflaged dramatically increases the odds for female birds to survive for years and raise multiple clutches in their lifetime.

In the case of hummingbirds, males will often display impressive iridescent scale-like feathers on the underside of their necks, while females will usually forgo this display with a white underbelly and neck. If you see a hummingbird without “sequins” on its neck returning to your feeder multiple times per day, it’s likely that she has a nest somewhere nearby and is slurping up the sugar water to return to her young. Hummingbirds will store and partially digest food in their “crop,” a storage space between their mouth and stomach, then regurgitate it back into the baby hummingbirds’ mouths. This would be pretty disgusting behavior for a human, since we don’t have a crop.

You’ve probably noticed that hummingbirds don’t fly like other birds. Comparing a hummingbird to a chickadee, you’ll notice that the hummingbird can stop and “levitate” in mid-air, while the chickadee cannot. Comparing the two to human flight machines, a hummingbird acts similarly to a helicopter while a chickadee is more like a plane. Hummingbirds beat their wings incredibly quickly, averaging 15 beats per second but being capable of pushing that number up to 80 beats per second if they’re in a hurry. The pattern in which hummingbirds beat their wings is also different from normal birds, as they will create a figure eight pattern with their wingtips.

Have you ever gone kayaking? Have you tried paddling at your maximum speed for 15 minutes on end? Chances are, your whole upper body is going to feel the burn, and you’ll have worked up a good sweat by the end of it. This is the closest approximation to what a hummingbird endures in flight. 

Producing enough energy to keep up flight requires an extremely efficient metabolism. Hummingbirds consume almost nothing but carbohydrates and protein, which is converted at almost 100% efficiency. A human athlete at their very peak performance will only have about 30% metabolic efficiency. This also means that hummingbirds need food constantly to stay alive. That is, until they go to “sleep.”

Hummingbirds require vision to feed. They’re attracted to brightly colored flowers and insects. This means hummingbirds cannot effectively feed at night — so what do they do if they can’t survive more than 60 minutes without a meal?

They enter a state called torpor, during which time their metabolic function drops to nearly 0%. While humans continue to breathe, sweat and digest food at a slower rate during sleep, these functions virtually stop for hummingbirds. Their internal body temperature even drops to a level that would be lethal for any other animal. Shortly before dawn, a chemical reaction occurs in the hummingbird that triggers it to begin “waking up.” This process starts with rapid muscle contractions that cause shivering, with those little bursts of energy generating heat inside of the bird’s body that begins to return it to its normal state. This takes anywhere from 20 minutes to an hour, then the hummingbird will start the day to forage for food.

There are three documented species of hummingbirds that spend time in Bonner County. The rufous hummingbird, which migrates up to 3,900 miles in a single year, is a common sight in our neck of the woods. These hummingbirds will often present with a copper-colored backside and white belly, while males will have a ruby red neck. It’s not unusual for there to be green on a rufous hummingbird, but the copper color is a dead giveaway. They are also one of the most aggressive hummingbird species, and will actively dive-bomb other hummingbirds and humans near their favorite feeder.

Black-chinned hummingbirds are a little rarer around here. They will usually have a green or gray back and white belly. The males are easily identifiable, as they have a deep purple or black iridescent neck.

Calliope hummingbirds can appear deceptively similar to rufous hummingbirds if you only see them in passing. Calliope hummingbirds will usually appear as green and white, with females having black speckles along their face and neck, while males will have magenta neck feathers that look like long slashes. They like to nest in conifer trees, and have been observed frequently hunting insects with a technique called “hawking,” where they will perch on a branch and observe the patterns of their prey before dive-bombing them and intercepting them mid-flight.

Have you seen other hummingbirds around? Take a picture and share it with the library or the Reader. There’s so much negativity in the world, sometimes you just want to see a cute little bird to feel better.

Stay curious, 7B.