Torpor, Hibernation, and Estivation

Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B. He will thus, without expenditure of work, raise the temperature of B...in contradiction to the second law of thermodynamics. 

The amount of nectar available to a broad-tailed hummingbird determines whether it goes into torpor during the night. 

A hummingbird in torpor has a low metabolic rate and so uses little energy. 

To meet its energy demands, a hummingbird that does not go into torpor must consume large quantities of nectar just before roosting. 

FIGURE 6.15.1 When food availability is low, hunmiingbirds switch to a state of torpor. (From Molles, M.C. Jr., Ecology Concepts and Applications McGraw-Hill, New York, 1999. With permission.) 

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Contrast torpor, hibernation, and estivation. What is similar, and what is different among them What environmental conditions trigger each ... 

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