Rufous hummingbird perched WM

Imagine having to eating 2-3 times your body weight in food every day just to survive!  That if you have a bad day of not finding enough food you are going to starve to death! Hummingbirds push the limits and live their lives on the edge. No wonder people rarely see them doing anything but eating.

Their incredibly high metabolic rate means that the only way they can survive the long nights without eating is to go into a form of hibernation, called torpor. Every night they lower their body temperature to prevent wasting energy trying to keep their internal temperature at around 38 degrees Celsius. Their heart rate slows to as low as 50 beats per minute (from over 800-1200) and respiratory rates are not detectable. Simply put they appear to be dead. A few hours before dawn they have an internal alarm clock that goes off that awakens them from this suspended animation. At this point they fluff themselves up, start to shiver and beat their wings. This generates enough heat to increase their body temperature a few degrees a minute. Total time to awaken from torpor takes about 20-60 minutes.  If they have budgeted their energy reserves well, once awake they have just enough energy to fly off and find their first meal of the day. Now try to imagine how much they need to eat to raise 2-3 chicks!

This photo is of a female rufous hummingbird after coming back from a successful feeding trip to feed her two rapidly growing chicks (photos to come down the road). She took a quick break to rest during a chilly morning in the Rockies.

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