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Dormancy is a state of reduced metabolic activity that many organisms adopt during periods of environmental stress.<ref>"dormancy." Encyclopædia Britannica Online</ref> The stress may be expected (e.g., winter and summer, two common times of dormancy) or unexpected (e.g., drought). Dormancy during winter and summer is called hibernation and aestivation, respectively.
Hibernation
As noted above, hibernation is a behavior of certain animals, particularly in cold climates, of entering dormancy as a means of coping with the vicissitudes of winter. While many animals will sleep more than usual during the winter, true hibernation involves dramatically reduced heartrates and body temperatures, generally over a single unbroken period of torpor.
Animals that hibernate include bears, the dormouse, the hedgehog, and many types of reptiles and amphibians.
Most birds migrate to avoid harsh seasonal conditions; the common poorwill, a type of nightjar, is the only bird known to hibernate. Historically, swallows were believed to hibernate at the bottom of ponds.
Aestivation
As noted above, aestivation is a behavior of certain animals, typically in hot climates, involving a period of dormant behaviour to avoid the extremes of summer. It is a rather less common behaviour than hibernation. Animals that aestivate include certain types of crocodile and lungfishes.
Non-biological uses
The words “dormancy” (noun) and “dormant” (adjective) are also used more generally to describe things that are not active. For example, a dormant volcano is one that is not erupting,<ref>Definition of "dormant"</ref> and the term “Dormant Commerce Clause” refers to situations in which Congress has not exercised its powers under the Commerce Clause.
- Snippet from Wikipedia: Dormancy
Dormancy is a period in an organism's life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions. Organisms can synchronize entry to a dormant phase with their environment through predictive or consequential means. Predictive dormancy occurs when an organism enters a dormant phase before the onset of adverse conditions. For example, photoperiod and decreasing temperature are used by many plants to predict the onset of winter. Consequential dormancy occurs when organisms enter a dormant phase after adverse conditions have arisen. This is commonly found in areas with an unpredictable climate. While very sudden changes in conditions may lead to a high mortality rate among animals relying on consequential dormancy, its use can be advantageous, as organisms remain active longer and are therefore able to make greater use of available resources.