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The Fascinating Hummingbird

This is the Ruby-Throated Hummingbird, and it is a fascinating creature.  It is a species of hummingbird that generally spends the winter in Central America, Mexico, and Florida, and migrates to Eastern North America for the summer to breed.  It is the ONLY hummingbird seen east of the Mississippi River in North America.  They are between three and three and a half inches long, with females being larger.

The mature male is easily identified with its characteristic red feathers on the neck.  But these feathers are not actually red.  Rather they contain an absence of pigment that reflects the red color when full spectrum light shines on the feathers.  Fascinating, huh?

Hummingbirds also have one of the highest metabolic rates of any animal, with heart rates up to 1260 beats per minute (the human heart beats up to 150 beats per minute), and oxygen consumption of about 4 ml of oxygen per hour at rest. During flight, hummingbird oxygen consumption per gram of muscle tissue is approximately 10 times higher than that seen in elite human athletes.

The hummingbirds arrived at Merica House on April 23rd, but the first week of May we saw a windchill of 20 degrees.  Yet, they survived!

A final fascinating feature of this bird is its ability to conserve energy on cold nights by entering hypothermic torpor. This is a short-term dormant state where the metabolic rate drops by 95%.  Their body temperature is maintained at a hypothermic threshold that is barely sufficient to maintain life.

To awaken from torpor, the bird vibrates its wing muscles which warms the blood supply, increases the heartrate and breathing. Then they reliably awaken two hours before dawn without any discernable cues from the environment.  Thus, it appears that the bird’s internal circadian clock triggers the arousal.  Fascinating!

Contributors: Sara Hiebert, Hummingbird Expert, Wikipedia, and Mark Wolsky, Landscape and Wildlife Photographer