Some desert-dwelling termites, or “white ants” as they are sometimes
misleadingly known—their closest relation is in fact the cockroach—have an
alternative solution to the problem of staying cool. These pale, moist creatures
are particularly vulnerable to high temperatures, drying out and dying within
minutes in hot sunlight. Most termite species live in colonies and excavate
underground nests where they live in cool, dark dampness. Some desert species,
however, also gather and pile desert soils to build towering structures of earth—
termite mounds—that can sometimes exceed 5 meters (16 ft.) in height (see Fig.
1 ). Termite mounds rapidly become baked hard in the heat and are a
conspicuous feature in many arid lands, especially in the deserts of southern
Africa and Australia.
The termite mound or tower does not contain the termites’ nest. The actual
dwelling area is below ground level as usual, directly under the mound, with
feeding galleries radiating into the surrounding soil, where the termites forage
for fragments of plants, fungi, and other foods. Instead, the mound serves as
protection, especially against termite-eaters such as the giant anteater and
against flash
floods from rare cloudbursts. The mound also serves as a natural airconditioning
plant. A network of holes, ducts, and chimneys allows air to
circulate freely, drawing heat away from the nest during the day—though
without taking too much valuable moisture—while preventing the nest cooling
too quickly at night.
Termite mounds are a useful feature of the desert landscape and provide in
miniature a paradigm of the interdependence of life-forms in the desert
environment, and indeed in any biome. Birds use them as perching and vantage
points. Cheetahs or kangaroos lie in their shade. Snakes, armadillos, jackals, or
other den-users may inhabit parts of the mound that the termites have deserted.
In Australia mulga parrots (Psephotus varius) often peck a nesting hole in a
termite mound rather than a tree, while sand goannas (Varanus gouldii) tear
open part of the mound to lay their eggs inside. The termites subsequently repair
the wall, providing a haven for the lizard’s eggs to develop within.
Atlas of the world’s deserts 142
Some of the most intriguing termite mounds are the slab-sided, sharp-topped,
squared-off structures found in the arid regions of northern Australia. Up to 4
meters (13 ft.) tall, they look like the tips of giant chisels sticking up from the
hard, red earth. Their builders are known as magnetic, or compass, termites
(Amitermes meridionalis) because the broad sides of the mounds are always
oriented north—south. This remarkable phenomenon is due, however, not to any
magnetic-detection skills on the part of the termites but to the fact that they build
the mound in such a way as to maintain an even temperature both within and
beneath the structure for as long as possible each day. At dawn and dusk the sun
shines on a broad side of the mound, keeping it warm for as long as possible, but
at midday the sun blazes down
n the small surface areas of the sharp edges and
top, preventing overheating.