Dirk OdenDirk Oden




About SP
Science Humor





Hummingbirds in a Nutshell
(They would just about fit!)

     If you are like most people you have seen and heard them. You are amazed by their acrobatic adventures and appreciate the beauty of their iridescent coloring. But you may not know a lot about these little creatures. If you wonder if the life of a hummingbird is as interesting as it appears, you won't be disappointed.
    Hummingbirds are unique in many ways. They are the only birds that can truly hover or fly backwards. They are almost fearless, and wild hummingbirds can often be easily coaxed into perching on a finger at a feeder. Males put on breathtaking aerial displays during the breeding season and demonstrate amazing maneuverability during in-flight disputes over territories. Watching such energy and vigor it is hard to believe that hummingbirds live within just hours of death!

Energy Shortage.
    Hummingbirds are among the smallest of vertebrates and have the highest metabolism of all animals (about 30 times the human metabolic rate). This high metabolism (converting food energy to energy the body uses) is due mostly to their small size. The cells of warm-blooded animals produce heat during metabolism. A large animal, such as an elephant, has so many cells inside its body producing heat that the problem becomes getting rid of excess heat. With a small animal, however, heat is lost much more quickly to the environment and the problem becomes getting enough energy to stay warm. In fact, a warm-blooded animal smaller than a hummingbird (or shrew--they are about the same size) could not exist because it could not take in food fast enough to keep itself warm. A hummingbird deprived of food would die within a few hours!
    Hummingbirds have evolved a unique method of foraging--hovering. This ability allows hummingbirds to find a food source not available to other birds. Wildflowers typically grow too high off the ground for a standing bird to reach and are too flimsy to support a perching bird. Hummingbirds get energy by feeding on the sugar-rich nectar of wildflowers, consuming three times their own weight in nectar daily. They also eat a few insects during the day to provide protein and other nutrients.

Conserving Energy.
    Because they lose heat so rapidly, hummingbirds are often not able to maintain normal body temperatures during the night. To conserve energy they shut down and become "torpid." Torpidity is a sort of temporary hibernation in which the hummingbird's temperature can drop from the normal 104 F to a mere 54 F and the metabolic rate decreases significantly. Also, studies have shown that the patterns hummingbirds follow when feeding are very efficient. In fact, most hummingbird behavior can be explained in terms of increasing energy efficiency. Although I like to think that hummingbirds will sit on my daughters' fingers while drinking at the feeder because the birds are able to recognize my daughters' kind intentions, I suspect they recognize the opportunity to rest while feeding and know they could escape instantly if they felt threatened in any way.

A Hummingbird Paradox?
    If hummingbirds need so much energy, why do they spend so much time perched doing nothing? This question plagued scientists for some time. If you spent a day following a hummingbird (good luck keeping up!) you would find it spent about 75% of its day perching, and only 20% of its day feeding. A group a four scientists (science is seldom an individual effort) led by Jared Diamond discovered the answer. During the perching time, hummingbirds are digesting nectar as rapidly as possible and have nothing to gain by feeding until their storage crops are at least half-empty (Do most people fill up their cars with gas when the gauge reads three-fourths full or wait until it's less than half?). It turns out that with the typical pattern of feed for one minute, perch for three minutes, hummingbirds are taking in energy as fast as their digestive system allows.

Hummers Here.
    Twenty-three species of hummingbirds have been verified in the United States, eight of which commonly breed north of the Mexican border. Seven species have been recorded in Colorado, but the most commonly seen hummingbirds in the state are the Broad-tailed, Black-chinned, and Rufous.
    Broad-tailed and Black-chinned hummingbirds winter in Mexico and arrive in Colorado in late April, remaining as breeding residents until late September. Broad-tailed hummingbirds are fairly common from the foothills to timberline regions. Males have a brilliant iridescent red chin (frequently causing them to be misidentified as the Ruby-throated hummingbird of the eastern states). Black-chinned hummingbirds are usually found in the lower valley to foothills regions of the state.
    Rufous hummingbirds are easy to recognize because of their brilliant orange coloring. If you have watched any at a feeder, you know they are the most aggressive of all hummingbirds. I have never coaxed one to sit on my finger and wonder if anyone has.
    Rufous hummingbirds are extensive travelers. They begin migrating from their wintering grounds in Mexico as early as January, and, following the west coast of Mexico, enter the United States in March. Rufous hummingbirds follow the West Coast to their breeding grounds in the Pacific Northwest (some go on to Alaska) and then begin migrating south through the Rocky Mountains in June, arriving in the Colorado mountains in late July. Depending on weather, food supply, and time of year, individual Rufous hummingbirds will stay in one location for one or two weeks building fat reserves before moving on.

Private Showings.
    If you put out a feeder this summer, you won't be disappointed. A variety of commercial designs are available. Dissolve one part sugar in four parts water. You don't need food coloring if the feeder has bright red on it. Be prepared for amazing acrobatic antics as hummers vie for control of a valuable resource. When a hummingbird hovers at your feeder, listen to the whir of the wings. Step closer and feel the turbulence on your face. Look for the figure-eight pattern that only a hummingbird's wings can make. Watch for the sun to bounce off the iridescent feathers and give you your own private light show. Slowly extend a patient finger and you might feel the slightest grip as two tiny feet find a perch. Don't you know, the hummer could use a rest.

1997, 2006  Dirk Oden

Hummingbird on finger image 2007 Dirk Oden




This site was last updated 08/03/07