Alex Tolmachoff, age 9, of Buckeye, Arizona, for his question:
Do desert animals hibernate in summer?
The desert is drenched with dazzling midsummer sunshine. The soft sands and the colorful rocks are hot and dry. For miles, the silent, sweet scented place seems deserted. Yet we know that the desert is never really deserted. It is populated with countless birds and mammals, reptiles and amphibians. As a rule, we don't notice them because they stay very still when visitors pass by and their colors blend in with the desert scenery. But right now many of these creatures are not around because they are sleeping soundly through the hot midsummer season.
We know that beavers, bears and woodchucks hibernate through the winter. They hide in cozy corners and sink into a deep sleep until spring returns with food supplies and warmer weather. Most deserts are warm and sunny places, even in winter. Here the animals do not have to hibernate to escape the cold. But the summer season may be too hot for them and perhaps too dry. They do what the cold country animals do in winter, but we do not call it hibernation. This is estivation, sometimes spelled aestivation.
Creatures that estivate take a long sleep when the summer weather gets too hot and too dry. When the long heat waves dry up the last trickles of water in the canyons, the desert frogs creep under moist rocky ledges and estivate until the dry spell is over. The desert snail coils up inside his shell, seals the opening with a papery door and takes a long sleep. Certain fishes and turtles bury themselves in the mud and estivate until things get wetter and better. When the mild winter returns, these summer sleepers wake up to enjoy the desert ponds and streams.
The kangaroo rat and the kangaroo mouse also estivate during the summer. They do not mind a dry desert spell because they never drink water. But very hot weather seems to be too much for them. The kangaroo rat goes down his burrow and seals his doorway with a wad of earth. In his underground room he sleeps for days, beside his pantry of stored seeds. The little kangaroo mouse goes down his 12 inch tunnel and curls himself up in a ball. His normal temperature is 102 degrees. But when he sinks into his deep, long summer sleep it drops to 60 degrees and his heartbeat slows down. There are stores of seeds beside him but he does not wake up to eat for a month or more.
Some of the desert squirrels estivate, but not all of them. The Mojave ground squirrel may doze through seven months of the year, from August until about March. In August, he estivates to escape the summer heat waves. When the cool fall weather arrives, he stays right where "he is and hibernates through the winter. Meantime, his cousin the antelope squirrel keeps busy all through the year. In hot weather he goes down his burrow and washes his fur to stay cool. But he never takes time off to estivate or hibernate.
Many creatures of jungles and other hot summer regions also estivate. In Egypt, a certain snail may forget to wake up and sleep on through the winter and next summer. In India, certain catfish estivate in the mud of dry streams. In Africa, a famous lungfish burrows in the mud and lines a small room with goo, leaving a breathing tube to get air while he estivates.