Pretty much everywhere you go in the semi-arid regions of Australia, the landscape is dotted by termite mounds. In the north of Queensland, I had seen gnarled, gray termite mounds that were three to five feet high standing amidst fields of golden grasses. As I had neared Darwin, I saw three- to five-foot-high termite mounds both punctuating the grasslands, but also leaning against collapsing trees. But in Kakadu, we saw astonishing mounds that were as much as 20 feet tall.
Australia’s “white ant” is actually unrelated to ants, though the termites do look quite like colorless ants. They also have a social order that is reminiscent of ants, living in large colonies with workers, soldiers, and an egg-laying queen. There are more than two hundred species of termite in Australia. Most eat grass or leaf litter, but many species eat wood, and there is a constant battle in areas where the wood-eating varieties thrive to keep them from eating one’s home. (Of those that eat wood, most prefer dead wood, so they fill a need in the wild, disposing of dead trees. But if the dead wood happens to be the infrastructure of your bungalow, then it’s a problem.)
Termites need humid, protected environments, so they create massive nests, almost entirely underground. To stay protected, they build mud shelter tubes for traveling to feeding sites—and a mud sheltering tube is sometimes the first indication that a tree or house has visitors.
The giant mounds are made of mud and termite saliva, and they are of a hardness somewhere between baked pottery and concrete. These mounds stand above the nests and help control airflow and temperature in the extensive network of subterranean tunnels.
Because they are largely made of mud, the color of the land affects the color of the termite mounds. When I reached the iron-rich Hammersleys in Western Australia, the termite mounds I saw shared the rich rust color of the surrounding soil, but in Kakadu, they were gray. However, in Kakadu, they also appeared more carefully constructed, more castle-like. Still, in both places, standing next to a twenty-foot hill created by insects makes an impression. The mound below was one we stopped to admire on our last day in Kakadu.