Hibernation and Estivation Certain species of animals hibernate during cold weather in the winter. Some animals estivate during hot weather in the summer. Both
hibernation and estivation are types of dormancy. An animal that is hibernating or estivating may appear to be asleep. However, dormancy is
different from sleep. During a time of dormancy, an animal's body processes usually slow down. Its heart rate decreases; it does not need to eat or
drink; and it uses less oxygen than it does when it is not dormant.
Some animals estivate during long periods of heat and drought when little water is available. Before going into estivation, an animal will
often find a safe shelter in which to estivate. North American desert tortoises, for example, burrow below the soil before going into estivation. They
remain underground until the period of heat and drought is over.
Other animal species hibernate during long periods of cold. American toads, for example, dig burrows during winter when temperatures are
low and food is hard to find. However, not all frogs are capable of digging. The spring peeper frog and the wood frog take shelter in logs or under
rocks and spend the winter there. Animals emerge from hibernation when the weather warms up.
Which conclusion can be drawn from this passage?
1. Animals are more likely to hibernate than to estivate.
2. Animals that estivate in the summer also hibernate in the winter.
3. Animals go into dormancy to help them survive harsh conditions.
4. Animals take shelter underground during a period of dormancy.
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