state of decreased physiological activity in an animal

Torpor is a physiological state of the body. It occurs in some small warm-blooded animals when food is scarce.

Some animals have periods of torpor every day, including hummingbirds.[1][2] So do some small mammals, for example, rodent species (such as mice), and bats.[3] Many small marsupials also have daily periods of torpor.[4]

Torpor is a well controlled thermoregulatory process. It is not the result of switching off thermoregulation.[5]



  1. Hainsworth F.R. & Wolf L.L. 1970 (1970). "Regulation of oxygen consumption and body temperature during torpor in a hummingbird, Eulampis jugularis". Science. 168 (3929): 368–369. doi:10.1126/science.168.3929.368. PMID 5435893. S2CID 30793291.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  2. "Hummingbirds". Migratory Bird Center, Smithsonian National Zoological Park. Archived from the original on 2008-02-14.
  3. Bartels W; Law B.S. & Geiser F. 1998 (1998). "Daily torpor and energetics in a tropical mammal, the northern blossom-bat Macroglossus minimus (Megachiroptera)". Journal of Comp. Physiol. B. 168 (3): 233–239. doi:10.1007/s003600050141. PMID 9591364. S2CID 16870476.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  4. Geiser Fritz 1994 (1994). "Hibernation and daily torpor in marsupials – a review". Australian Journal of Zoology. 42 (1): 1–16. doi:10.1071/zo9940001. S2CID 84914662.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  5. Geiser, Fritz 2004. (2004). "Metabolic rate and body temperature reduction during hibernation and daily torpor". Annu. Rev. Physiol. 66 (66): 239–274. doi:10.1146/annurev.physiol.66.032102.115105. PMID 14977403.{{cite journal}}: CS1 maint: numeric names: authors list (link)