Its common to see
some birds relaxing or sleeping on one leg. But why ? This simple question had always baffled me
till I took to bird photography seriously and began to observe their behavior.
I remember in childhood whenever I asked the elders that why birds, especially
egrets stand of one leg, pat would come
the reply, “its prayer time”. During my recent visit to Siswan dam, I saw a
large number of Ruddy Shelducks basking while standing on one leg. Now I know these
species understand better why to relax on one leg. They seem to
be aware that they have adaptations to manage heat loss.
We all know most of
the birds have naked legs without insulating feathers. Their feet being closer
to environmental temperature, they don’t lose as much heat as they would if
they were at body temperature. The widely known theory
is that by standing on one leg, they conserve heat and prevent at least it from heat loss. A bird
with its one foot tucked up reduces by half the amount of heat lost through its
unfeathered limbs. In other words, the
arteries that transport blood into the legs of birds are in contact with the
veins that return blood to their heart. The warm arteries heat the cooler veins
which also cool the arteries. Also, during winter some species flutter
their feathers to cover both legs. Interestingly, to get extra warmth,
they tuck their beaks under their shoulder feathers, but not under their wings.
Ever
thought what makes birds comfortable in this posture of standing on one leg for
a long time. Birds don’t have muscles in their feet or legs. Each of their leg has
two flexor tendons that run from shoulder to the toes. With change in angle of their ankle they are
able to close and lock their feet around a perch. Therefore they are able
to sleep while standing on one leg.
