Torpor

Torpor

Anna's hummingbird in nocturnal torpor during winter in Vancouver, BC

Torpor is a state of decreased physiological activity in an animal, usually by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. It is a short-term hibernation-like state that can last for a few hours or overnight.

Mechanism

Torpor involves a significant drop in body temperature and metabolic rate. During torpor, an animal's heart rate and respiration slow down, conserving energy. This state is controlled by the animal's circadian rhythm and is often triggered by environmental factors such as temperature and food scarcity.

Types of Torpor

Daily Torpor

Daily torpor occurs in small mammals and birds, allowing them to conserve energy on a daily basis. Animals such as hummingbirds and bats enter torpor to survive periods when they cannot feed.

Seasonal Torpor

Seasonal torpor, or hibernation, is a prolonged form of torpor that occurs in response to seasonal changes. Animals like bears and ground squirrels enter hibernation to survive winter months when food is scarce.

Benefits of Torpor

Torpor allows animals to conserve energy and survive in harsh conditions. By reducing metabolic demands, animals can extend their survival during periods of food scarcity or extreme temperatures. This adaptation is crucial for survival in environments with unpredictable resources.

Examples of Animals Using Torpor

Hummingbirds

Hummingbirds are known for their high metabolism and energy demands. They enter torpor at night to conserve energy, especially in colder climates or when food is not readily available.

Bats

Bats use torpor to conserve energy during the day when they are not active. This is particularly important for species that feed on insects, which may not be available during certain times of the year.

Marsupials

Some marsupials, such as the pygmy possum, enter torpor to survive periods of food scarcity and cold temperatures.

Related Pages

• Hibernation
• Circadian rhythm
• Metabolism

References

• Geiser, Fritz. "Metabolic Rate and Body Temperature Reduction During Hibernation and Daily Torpor." Annual Review of Physiology, vol. 66, 2004, pp. 239-274.
• Ruf, Thomas, and F. Geiser. "Daily torpor and hibernation in birds and mammals." Biological Reviews, vol. 90, no. 3, 2015, pp. 891-926.

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  Anna's hummingbird in nocturnal torpor during winter in Vancouver, BC