1 Tahrcountry Musings: Why flamingos stand on one leg

Monday, August 17, 2009

Why flamingos stand on one leg

Have you ever wondered why flamingos stand on one leg? I have pondered over this many a time. Several hypotheses have been offered in the past, but none of them were very convincing.

Here comes a convincing explanation. Scientists Matthew Anderson and Sarah Williams from Saint Joseph's University in Philadelphia think they have the answer. Their studies indicate that Flamingos stand on one leg to regulate their body temperature
The research began by seeing whether the birds show any preference over which side of their bodies they use for various tasks. They found that flamingos prefer to rest with their heads on one side more than the other. Which side a flamingo rests its head is determined by how aggressive it is toward others in the flock. This led the researchers to investigate whether flamingos also prefer to stand on one leg more than the other, and why they stand on one leg. They spent several months observing the habits of captive Caribbean flamingoes (Phoenicopterus ruber) at Philadelphia Zoo, Pennsylvania.

The researchers found that flamingos prefer to stand on one leg far more often when they are standing in water than when standing on land. As water invariably draws away more body heat, this result supports the thermoregulation hypothesis. In other words birds stand on one leg to conserve body heat. The birds also switch their legs to avoid one leg becoming too cold.

The scientists do not rule out the possibility that there may be added benefits as well as conserving body heat.

Details appear in the latest issue of journal Zoo Biology


Chris said...

Very interesting theory. I learned something new today. ;-) I wonder if the same behavior can be found in other water birds.

Mohan Alembath said...

Hi Chris,
Here is something from Stanford that might be of interest to you

When it is cold, the lack of insulation on the legs makes them a site of potential heat loss. To minimize such loss, the arteries and veins in the legs of many birds lie in contact with each other and function as a countercurrent heat exchange system to retain heat. Arterial blood leaves the bird's core (trunk) at body temperature, while venous blood in the bird's foot is quite cool. As the cool blood returns toward the core, heat moves by conductance from the warm arteries into the cool veins. Thus, arterial blood reaching the feet is already cool and venous blood reaching the core has already been warmed. In addition, by constricting the blood vessels in its feet a bird may further decrease heat loss by reducing the amount of blood flow to its feet at low temperatures. Thus while the core temperature of a duck or gull standing on ice may be 104 degrees F, its feet may be only slightly above freezing.

Behavior also can play a significant role in reducing the amount of heat lost from unfeathered surfaces. By standing on one leg and tucking the other among its breast feathers, a duck or gull on ice reduces by half the amount of unfeathered limb surface area exposed; by sitting down and thus covering both legs, heat loss from the limbs is minimized. In cold weather, juncos, sparrows, and other finches foraging on the ground frequently drop down and cover their legs and feet with their breast feathers while pausing in their search for food. On cold or windy days, shorebirds often can be seen resting with their beaks tucked away among their feathers, sometimes combined with standing on one leg or sitting. And, of course, birds can further enhance their effective insulation by fluffing out their feathers to increase the thickness of their "coat."

Chris said...

Very good info. Apparently, all shore birds do it. It's a nice tidbit to share over dinner.

It would be interesting to find out if dipping a limb in water will increase blood pressure. I assume it will since your body will adapt by pumping more warm blood to the cold limb.