Editing Dormancy (section)

== Animals ==
{{Dormancy}}

=== Hibernation ===
{{main|Hibernation}}

Hibernation is a mechanism used by many mammals to reduce energy expenditure and survive food shortages over the winter. Hibernation may be predictive or consequential. An animal prepares for hibernation by building up a thick layer of [[body fat]] during late summer and autumn that will provide it with energy during the dormant period. During hibernation, the animal undergoes many [[Physiology|physiological]] changes, including decreased [[heart rate]] (by as much as 95%) and decreased [[body temperature]].<ref>{{Cite web|url=https://www.colby.edu/academics_cs/courses/BI312/upload/Hibernation.pdf|title=Molecular and metabolic Aspects of Mammalian Hibernation|last=Bert B. Boyer|first=Brian M. Barnes|date=1999|website=www.colby.edu|url-status=dead|access-date=2017-08-22|archive-url=https://web.archive.org/web/20200125154524/https://www.colby.edu/academics_cs/courses/BI312/upload/Hibernation.pdf|archive-date=2020-01-25}}</ref> In addition to shivering, some hibernating animals also produce body heat by non-shivering thermogenesis to avoid freezing. Non-shivering thermogenesis is a regulated process in which the proton gradient generated by electron transport in mitochondria is used to produce heat instead of ATP in brown adipose tissue.<ref>{{Cite journal|last1=Kozak|first1=Leslie P|last2=Young|first2=Martin E|title=Heat from calcium cycling melts fat|journal=Nature Medicine|volume=18|issue=10|pages=1458–1459|doi=10.1038/nm.2956|pmid=23042344|year=2012|s2cid=5177743}}</ref> Animals that hibernate include [[bat (animal)|bats]], [[ground squirrel]]s and other rodents, mouse lemurs, the [[European hedgehog]] and other insectivores, monotremes and marsupials. Although hibernation is almost exclusively seen in mammals, some birds, such as the [[common poorwill]], may hibernate.

=== Diapause ===
{{main|Diapause}}
{{further|Embryonic diapause}}
Diapause is a predictive strategy that is predetermined by an animal's [[genotype]]. Diapause is common in [[insect]]s, allowing them to suspend development between autumn and spring, and in [[mammals]] such as the [[Roe deer#Reproduction|roe deer]] (''Capreolus capreolus'', the only [[ungulate]] with [[embryonic diapause]]{{Citation needed|date=January 2012}}), in which a delay in attachment of the [[embryo]] to the [[Uterus|uterine]] lining ensures that [[offspring]] are born in spring, when conditions are most favorable.

=== Aestivation ===
{{main|Aestivation}}
Aestivation, also spelled ''estivation'', is an example of consequential dormancy in response to very hot or dry conditions. It is common in [[invertebrates]] such as the [[Helix (genus)|garden snail]] and [[worm]] but also occurs in other animals such as [[lungfish]], [[salamanders]], [[desert tortoise]]s, and [[crocodiles]].

=== Brumation ===
While [[endotherm]]s and other [[heterotherm]]s are described scientifically as [[hibernation|hibernating]], the way [[ectotherm]]s such as lizards become dormant in cold conditions is very different, and a separate term was coined for it in the 1920s: ''brumation''.<ref>{{cite web|url=http://lllreptile.com/info/library/care-and-husbandry-articles/-/reptilian-brumation/|title=Reptilian Brumation|access-date=2007-12-25|archive-url=https://web.archive.org/web/20120304060505/https://lllreptile.com/info/library/care-and-husbandry-articles/-/reptilian-brumation/|archive-date=2012-03-04|url-status=dead}}</ref> It differs from hibernation in the metabolic processes involved: energy is stored in [[glycogen]] in addition to or in place of fats, and periodic water intake is required.<ref>{{cite web|url=http://infinitespider.com/hibernating-mammals-brumating-reptiles-whats-difference/|title=Hibernating Mammals and Brumating Reptiles: What's the Difference?|date=20 January 2014}}</ref>

Reptiles generally begin brumation in late autumn (more specific times depend on the species). They often wake up to drink water and return to "sleep". They can go for months without food. Reptiles may eat more than usual before the brumation time but eat less or refuse food as the temperature drops. However, they do need to drink water. The brumation period is anywhere from one to eight months depending on the air temperature and the size, age, and health of the reptile. During the first year of life, many small reptiles do not fully brumate, but rather slow down and eat less often. Brumation is triggered by a lack of heat and a decrease in the hours of daylight in winter, similar to hibernation.{{cn|date=August 2024}}