A wondrous world under the ground
Jul 23 2014
A burrow is not just a hole or a tunnel dug up by the animal, it is also a very significant way to control various climatic difficulties, especially extreme temperatures. In a desert or arid ecosystem where forest cover is very scanty, most animals use such burrows or dens. They also live in burrows to get moisture from it, and retain the water level of their bodies. They often keep digging and bringing wet sand to cool down in the hot weather. This can be seen with foxes, hyenas and wolves.
Rodents are by far the most clever and keep multiple openings to their burrows. In fact, they keep shutting and closing some openings as per the flow of wind, so that coolness and humidity can be maintained in a burrow. For instance, a colony of rodents called the Indian desert jird can excavate tonnes of soil from their burrows every day. It is estimated that this species, which has a population of 200 to 450 or above per hectare, can excavate six trucks of soil with a capacity of nine tonnes per sq km.
Hyenas and foxes keep more than one active den at a time, so that they can keep using them from time to time. They change them and adopt new ones as per threat and availability of food near the den. The shape and size of the den and burrow depends on the species as well as the type of soil and ground hardness. During the rainy season, these become wet or get submerged in the water, so many rodents and reptiles abandon them for dryer places as too much dampness in a burrow can infect it with fungus.
Some signs give us an indication whether an animal is using a particular den or not. For instance, you can make out that hyenas are actively using a den when you see bones and dry hide of various animals scattered around. Similarly, in the Thar desert the Indian desert jird burrow will have various half-eaten plants strewn all over that have been consumed by these rodents. The size and number of den or burrow openings also reveal that which animal is using it. Fresh excavation marks and new soil near the opening also suggests whether it is a live den.
These indirect signs are very significant for wildlife researchers. Small mammals and burrowing animals are very important for our ecosystem, which is why we go to such lengths to explore their habitats and their home-preservation methodologies and gain an insight about the mysterious, wondrous world under the ground.
(The writer is a conservation biologist at Tiger Watch, Ranthambore)