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Hibernation is the key to winter survival for many small mammals. By strongly suppressing metabolic rate, falling into a deep torpor and letting body temperature (Tb) drop to near ambient levels, hibernators can save as much as 90% of the energy that would otherwise be needed to keep their bodies warm (Tb ~37°) throughout the winter. During hibernation all body functions are suppressed to low levels. For example, ground squirrels hibernating with a core Tb of 5°C show a heart rate of only 5-10 beats per minute compared with the normal resting values of 350-400 beats per minute. Breathing drops from greater than 40 to less than1 breath per minute and breathing patterns in many species can include long periods of breath-hold (called apnea), ranging from minutes to hours. Metabolic rate in hibernation (at a Tb of 0-5°C) is typically only 1-5 % of the normal resting rate at 37°C. The biochemical and physiological mechanisms that regulate hibernation are fascinating and exploration of these is not only key to understanding this amazing phenomenon but may also illuminate answers to applied problems in human health such as how to extend the viability during cold storage of mammalian organs removed for transplant or how to limit atrophy (muscle wasting) during long periods of skeletal muscle inactivity.


Links to Storey lab Review articles about hibernation

Links to Popular articles about hibernation;  for an easy-to-read general article about Animal Cold Hardiness, also see   PDF


Hibernating mammals in the Storey lab

These are the hibernating mammals that we work on in the Storey lab.
See photos below.

Ground squirrels


13-Lined ground squirrel (Spermophilus tridecemlineatus)

Little brown bat (Myotis lucifugus)

Richardson’s ground squirrel (Spermophilus richardsonii)

Meadow jumping mouse (Zapus huddonius)

Golden-mantled ground squirrel (Spermophilus lateralis)

White-tailed prairie dog (Cynomys leucurus)

European long-tailed suslik (Spermophilus undulatus)

Black-tailed prairie dog (Cynomys ludovicianus)

The 2 main model hibernators that we study in the Storey lab are:

Photo 1: 13-Lined ground squirrel, Spermophilus tridecemlineatus

Photo 2:  Little brown bat, Myotis lucifugus

        Description: 13line

Photo 3:  Torpid ground squirrel.

Description: hib squirrel 1-sm-2


We have also studied some aspects of hibernation in several other small mammals including:

Photo 4: Richardson’s ground squirrel, Spermophilus richardsonii  

Photo 5: Golden-mantled ground squirrel, Spermophilus lateralis:

Description: RGS-1-sm

Description: IMG0160


Photo 6:  Black-tailed prairie dog, Cynomys ludovicianus

Photo 7: White-tailed prairie dog, Cynomys leucurus

Description: Black tailed prairie dog

Description: white tailed prairiedog-2

Photo 9:  European suslik, Spermophilus undulatus

Photo 10:  Meadow jumping mouse, Zapus hudsonius:

Description: citellus_undulatus1

Description: Zapus