The steadiest place around
Why Do Animals Dig Burrows?
A metre underground it is the same temperature in a heatwave and a frost. That is worth an enormous amount of digging.
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Step 1 of 5
Soil is very slow to change temperature.
Heat creeps through soil at a crawl. A hot afternoon barely reaches a hand's depth, and by a metre down the whole difference between summer and winter has smoothed away.
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Step 2 of 5
So a desert animal simply goes down.
The desert surface can be lethally hot at midday. A metre below is mild, so most desert animals wait out the day underground and come out after dark.
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Step 3 of 5
The air down there stays damp.
A burrow traps humid air, so an animal loses far less water just by breathing. In a dry place that alone can be the difference between managing and not.
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Step 4 of 5
It is also a door only you fit through.
A tunnel sized to its owner keeps out anything bigger. Many burrows have a second exit as well, so being found at one end is not the end of the story.
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Step 5 of 5
Digging changes the ground itself.
Burrowing animals turn and mix soil, let water and air down into it, and leave tunnels other animals move into. Ground worked over by diggers grows more.
A prairie dog town can hold thousands of burrows joined together, with separate chambers for sleeping, for young, and for waste.
The short version
A burrow is a narrow door and a steady climate at once: a metre of soil evens out the whole year's weather.
Try it yourself
Dig a hand's depth into a sunny garden and feel the soil. The surface is warm and just below it is not.