The heron is a large water bird that, despite its massive body, walks on two long, thin legs. A simple but interesting mystery of nature: why does a heron stand on one leg?
This frequent question asked by visitors to the zoo and biologists, due to the presence of different theories, has several answers.
Rest on one leg
The reason why the heron is standing on one leg, the researchers originally called the bird's rest. Zoologists have concluded that this position of the legs helps to reduce the load on the legs and reduce fatigue, and also allows you to quickly escape from predators. This theory is confirmed in practice, since herons have a habit of sleeping, resting on only one leg.
Scientists further ruled out this assumption, since studies have shown that a heron needs more effort to move forward after being on one leg than after resting on two. Scientists also found that herons do not have preferences about which leg to stand on: left or right.
Other assumptions
Another proposed theory that a standing position on one leg helps the herons to maintain balance under windy weather conditions is subsequently rejected. Researchers abandoned some other original assumptions, such as the proposition that standing on one leg helps the heron circulate blood better, limiting the effect of gravity on the circulatory system.
Body thermoregulation hypothesis
Researchers found that a heron prefers to stand on one leg, much more often when it is in water than on land. Since water absorbs body heat, this behavior of birds supports the hypothesis of thermoregulation.
The thermoregulation hypothesis is that heron stands on one leg in order to maintain body temperature. While in the water, the heron alternates legs so that the supporting limb does not cool too much, since the water temperature is below air temperature. If the bird constantly stood on one leg or lowered both legs, it would risk a greater loss of heat and, as a result, tissue damage during the common cold, as it spends a lot of time in the wetland. This is proof that the thermoregulation function is the main reason why a stance heron uses only one lower limb.
Rete mirabile complex
Thermoregulation in the heron's body occurs using a form of branching of blood vessels called rete mirabile (lat. "Wonderful network"), which minimizes the heat loss of the bird. This complex of plexus arteries and veins is a heat exchanger, which consists in the fact that the internal temperature of the legs of the bird becomes much closer to the ambient temperature, and therefore, the limbs do not lose as much heat as they would at body temperature.
Heron stance as a way of hunting
Another popular theory suggests that a heron stands on one leg to look less suspicious of aquatic prey.Animals, seeing one leg of a bird, takes it for the stem of the plant and thus does not see danger. The bird hunts not only motionlessly in the water, but also approaching the victim in shallow water.
The characteristic pose of the heron provides constant readiness for movement: the bird can easily take a step and grab the living creatures of the reservoir (fish, frog, cancer) with a sharp jerk. However, British ornithologists believe that heron hunting does not depend on the position of the legs, and, leaning towards the theory of thermoregulation, they came to the general conclusion about the legs of the heron: when one leg is in the water, the second, raised and pressed under the abdomen, dries and warms.
Thus, the most probable and exhaustively substantiated the reason why the heron is standing on one leg is related to the thermoregulation of the bird's body, which consists in maintaining heat and avoiding hypothermia of the lower extremities during prolonged exposure to the aquatic environment.
The position of the legs of the heron is also determined by other factors — reducing the load on the limbs, maintaining balance, improving blood circulation, getting ready to move, getting food, etc. — which remain only the assumptions of the researchers.
Other water birds - flamingos, storks, ducks - also often stand on one leg, apparently for the same reasons as the heron.
