Hummingbirds In A State of Torpor

by Larry on January 22, 2008

Anna's Hummingbird

Anna’s Hummingbird (male) photo by Mark Schmitt

This incredible shot of the male Anna’s Hummingbird (Calypte annas) was taken by Mark and later enjoyed while listening to a beautiful piece of Baroque music entitled “Spem in Alium” by Tallis.  These beautiful combinations of nature and man make the human spirit soar.

These incredible little birds have an amazing way to protect themselves during very cold weather.  They lower their internal thermostat at night, becoming hypothermic, by going into a state of torpor.

Because of the hummingbird’s small size and lack of downy feathers, they quickly lose body heat at night when the temperature drops.  This is a huge problem for the hummingbird because they typically eat two to three times their own body weight in nectar and insects every day.  Even when hummingbirds are sleeping they have great metabolic demands they must meet to survive the night when they are unable to forage.

Anna's Hummingbird

Anna’s Hummingbird (male) photo by Mark Schmitt

As night falls, hummingbirds go into a state of torpor.  Torpor is a state of deep sleep where the bird lowers its metabolic rate by up to 95% allowing it to use up to 50 times less energy that it does when it is awake.  This type of torpor is known as noctivation or daily torpor and can occur on any night of the year.

In torpid, a hummingbird’s heart rate can go from 1260 beats per minute down to 50 beats per minute!  Their body temperature also drops well below the normal 104 degrees Fahrenheit.  Coming out of this state in the morning can take the bird over 20 minutes to awaken.  As this transformation occurs, they will vibrate their wing muscles and shiver, generating heat to warm their blood and allow them to make it to their first meal.

Living in northern California, I still have an Anna’s Hummingbird at my feeder, even though we live at an elevation of 1600 feet and have recently had snow storms.  Watch the video below of this bird’s behavior near the feeder on a cold day in the middle of January.

[youtube]http://www.youtube.com/watch?v=ZK7RAY7crUM[/youtube]

This was taken in the late afternoon.  It looks to me as if his heart rate is already slowing down and he spent a long time perched on that branch conserving energy.  If you live in an area where hummingbirds live year round, you should keep enough food in your feeders to keep them supplied with what they need to get through the winter months.  During these months there is seldom enough nectar to give them the energy they need.

Remember, hummingbirds will migrate according to hormonal changes triggered by decreasing length of days.  Nothing you do will change that response.  Therefore, you don’t want to stop feeding hummingbirds as long as there is just one in your area.  They will appreciate having a reliable source of food to get them through the winter.

If you are interested in Mark Schmitt’s photos you may email him here:

Mark Schmitt

Thank you for the use of those super photographs Mark!

Happy Birding!

Related Posts Plugin for WordPress, Blogger...
Did you like this? Share it:

{ 0 comments… add one now }

Leave a Comment

CommentLuv badge

Previous post:

Next post: