Hummingbirds

Hubby and I watched a fascinating program about hummingbirds on TV the other night. Hummingbirds originated in South America and only exist in the western hemisphere.  They are very aggressive little birds.  They exist high in the Andes and have a special type of hemoglobin that allows them to maximize oxygen so they are able to fly in oxygen concentrations similar to that on Mt Everest. They must eat every 20 minutes to support their high metabolic rate.  Their hearts beat at 1200 times per minute.  At night they go into a state of torpor where their heart rate drops to 70 per minute and their body temperature can drop to the 40 degree range.  The program said the hummingbird is still evolving with new species developing and their range is extending north. This is a ruby throated hummingbird (the only species in our area) that Hubby photoed at the bird feeder.