Fastest running bird
By Nutan Shukla

A DESERT bird of the American south-west is the world’s fastest-running flying bird. It rarely flies, but is nimble on the ground. With large X-shaped claws and strong legs, it can speed up to 24 km an hour. It has been clocked at 42 km an hour when chased by a car. It runs, almost arrogantly, with a straight neck, its wings slightly open as stabilisers, its legs going at 12 steps a second and its tail is used as a rudder that can turn the bird through 90 degrees without slowing down. By flicking its foot-long tail to one side, it can turn in mid-stride. When it is spread and raised above the bird’s back, the tail can help brake the bird to a quick halt.

Birds that live in the desert feed on a variety of things, from seeds and insects to snakes. The roadrunner, a clownish-looking bird belongs to the cuckoo family. It is non-brood parasitic, runs on the ground more than it flies. It is a great snake catcher and prefers to pursue its prey, which include lizards and invertebrates apart from fast moving snakes, on the ground. Once it kills its prey, it starts to swallow it. Often the snake is too long for the bird to get down all at once. Many roadrunners have been seen walking around for a whole day with a snake hanging out of their beak. It is swallowed inch by inch, as the lower end is digested.

Roadrunners have the most unusual physiology. Despite being a bird, it is, to some extent, a cold-blooded creature. During desert nights when the atmospheric temperature becomes very low, most birds increase their metabolism to maintain a constant temperature. For this, they have to burn their precious energy reserves. The roadrunner counters this problem by allowing the body temperature to fall slightly. This means it allows its body to save on the costs of ‘central heating’ by not burning the energy reserves. In the process of allowing the body temperature to fall, the bird becomes torpid (sluggish). The bird, thus, may be slow to respond to danger but the species has few predators. The slight disadvantage appears to be fairly unimportant.

Also very unusual is the way in which the semi-torpid roadrunner warms up in the morning. On the skin of its back, just between the wings, it has special darkly pigmented areas which absorb the sun’s energy more quickly, warming the skin and underlying blood vessels. The bird also fluffs up the feathers covering the patches so that the process is hastened. Without this mechanism, the roadrunner would use up to 50 per cent more energy in reaching a working temperature.

To enable its chick to have a regular dose of water, this bird has adopted a novel way. It holds a food item in the tip of its bill and when the chick approaches to grab it with gaping mouth the parent regurgitates water into the nestling’s bill before putting food.

The species has an exceptionally wide vocal repertoire, including an assortment of crowing and whining noises as well as cuckoo-like staccato hoots and clucks.

This fortnightly feature was published on January 10, 1999