Rufous hummingbirds visit Eagle County each summer
August 10, 2014
EAGLE COUNTY — Very few animals are as continually aggressive as the rufous hummingbird (selasphorus rufus). When they stake out a feeding area of flowers or a feeder with nectar, they are in charge. No other bird gets a chance to feed in that area. They are relentless at defending their territory.
Eagle County has three common hummingbirds: the rufous, the calliope and the broad-tailed hummingbirds. The male rufous body is orange with a bright orange throat called a gorget. The gorget on the broad-tailed is red. The gorget on the much smaller calliope is also red, but individual feathers are easy to distinguish. Those two birds have a green body. The female of all three look similar, with the same green upper body, but the female rufous has a small patch of red on the throat. The rufous has the ability of changing the position of the gorget feathers in such a way that the color can change from a dull red to an iridescent orange-red throat. They seem to flash this as a warning to other birds.
There are more than 325 species of hummingbirds. As a group, the hummingbirds are the smallest birds in the world. A rufous hummingbird is only about 3.5 to 4 inches in length, but don't let that size be deceiving. These guys are incredible fliers. The rufous makes a journey from Mexico to as far north as Alaska — an annual, one-way trip of 2,000-3,000 miles. The rufous nests farther north than any other hummingbird. They usually arrive in Eagle County around the Fourth of July and head back in August.
Hummingbird flight characteristics are unlike any other bird. They can fly forward, backward, sideways and straight up. Their hovering ability is well know and they may do backward somersaults when needed. This ability is made possible by the fact that hummingbirds move their wings forwards and backwards, and at the same time pivoting the wing up to 180 degrees at the shoulder, a movement called sculling. The wingtip traces a horizontal figure eight pattern and generates lift on both the forward and backward strokes. Rufous hummingbirds beat their wings at 52-62 wingbeats per second. All that work requires a huge amount of energy.
What these birds eat is a conundrum. Hummingbirds feed on flower nectar and the nectar put out in feeders. They have a long extendible tongue to reach deep into flowers and the nectar they obtain is actually diverted from the stomach and flows directly to the intestine. Many assume that is all they consume. Biologists also assumed that they were only getting liquid nourishment as they flit from flower to flower. Not so!
Hummingbirds in captivity that were fed only a diet of nectar died. Research has shown that these birds also consume a large number of insects they find stuck in sap, capture in the flowers or that they capture in flight. Hummingbirds also consume tree sap and seem to time their migrations north and south with the sapsuckers because those birds open up the tree bark to get to sap. They often arrive before a lot of flowers have bloomed and leave after most flowers have gone to seed. The tree sap helps the birds meet their needs. Fruits also provide the sugars they need, and they obtain it from damaged fruit.
Hummingbirds have the highest metabolism of any other birds. They are very active during the day. Their small size causes them to loose heat quickly. They have incredible appetites and consume two to three times their own body weight in nectar and insects each day. Since they cannot continue to feed at night they go into a state called torpor to conserve energy.
Torpor is a deep sleep like hibernation, but occurs at night. The hummingbird's metabolic rate decreases by as much as 95 percent and the hummingbird's night time body temperature is barely sufficient to maintain life. At daylight the birds become active again. There are stories of medicine men who would locate a hummingbird at night in a state of torpor, bring it into the village in the morning and show the seemingly dead bird to all. They would then cup it in their hands and blow their warm breath over the bird. The bird would emerge from torpor and fly off — proof of the power of the shaman.
The rufous hummingbirds in Eagle County are found in meadows and forests up to treeline. They breed in open areas and along forest edges. The female builds a nest in trees or shrubs from soft plant parts held together with spider webs. It is often covered on the outside with lichen, moss and bark. The nest is less than 2 inches wide and the 1 inch inner cup holds two eggs. They also live longer than expected, considering their size. One banded rufous survived for eight years.
What a unique and beautiful bird!
Rick Spitzer is the author of Colorado Mountain Passes, published by Westcliffe Publishers and available at The Bookworm, Amazon, and many stores across the state. The book provides photos and text about the history, lore, wildlife and scenery around the passes of Colorado. Rick is currently working on a book about the wildflowers of Eagle County.