Animals that fail to store enough fat are much less likely to survive, especially if the winter is particularly severe. Hibernators typically become fat prior to hibernating, as they must rely on the fat reserve as an energy source to carry them through the winter. The body temperature and metabolic rates of hibernating mammals drop significantly to low levels.
Hibernation is a period of deep torpor or winter dormancy that may last from weeks to several months, depending on the severity of the winter. Bats, for example, regularly become torpid on cold nights during the early spring and late fall, (i.e., just after or before they enter hibernation). During these periods, animals can avoid possible starvation by becoming torpid. Some small mammals, because of their high rates of metabolism (e.g., shrews, moles, bats), are vulnerable to starvation during periods of inactivity when they are not feeding. When an animal isn’t feeding, perhaps due to the effects of winter, it is advantageous for the animal to allow its body temperature and metabolism to drop to a lower level.
Generally, torpor occurs for short periods (hours to a day or so) and animals usually resort to torpor when their energy reserves are very low. Torpor is a period of inactivity by an animal in response to cold or other environmental conditions that might unfavorably affect the animal. Still, most mammals require sleep on a regular basis to perform effectively at most other daily functions. However, the mode of action of these substances and the physiological benefits of sleep are not well understood. During the hours mammals are active and awake, research has shown there is a build-up of sleep-inducing substances that accumulate in the central nervous system. In mammals, sleep is characterized with slight decreases in body temperature and extensive adjustments in various brain functions. Although sleep has been studied extensively, it is still poorly understood, even in humans. Clients occasionally inquire about their previous season’s mammal pests and wonder whether or not they might be “hibernating” in their attics, crawlspaces, wood sheds or within some earthen burrow next to the foundation or below their slab floors.ĭormancy in animals may be of five different types: sleep, torpor, hibernation, winter sleep and estivation. For pest management professionals, understanding dormancy in mammals is important.
This month we focus on “hibernation,” or more specifically, forms of dormancy in small mammals. This is because many of these animals “go down” or “hibernate” during the winter.īut why is it that some mammals hibernate while others do not? For example, why don’t commensal rodents or tree squirrels hibernate? Or moles, voles and shrews living outside in the cold seemingly frozen ground? And what happens to species that typically hibernate but encounter mild winters? When it comes to certain mammal pests, such as chipmunks, woodchucks, ground squirrels and bats, client calls for managing these animals are virtually non-existent during the winter months. In some areas, several inches (or more) of snow and ice are likely covering the ground. However, how and why hibernation occurs in some animals and not others is still a mystery.Many parts of the United States are now well into the cold winter months. Recently, they have discovered that animals that hibernate have a hibernation inducement trigger in their blood that allows them to detect changes in temperature and scarcity in food. Scientists are still not completely certain what triggers hibernation.To awaken, chipmunks will slightly shake themselves to raise their body temperatures. During hibernation, chipmunks will awaken several times to eat. Their gestation period is about 30-32 days.ĭiet: Chipmunks are omnivores and will eat insects in addition to nuts, seeds and fruits. Mating: Eastern chipmunks bi-annually in the spring and again in the summer. This further suggests that hibernation is an adaptation to the survival of extreme cold temperatures. While those that live in the southern part of North America where the weather is warmer tend to hibernate in December to late January. Chipmunks that live farther North usually go into hibernation around late October and reappear in the middle of March. Habitat: Chipmunks are ground burrowing animals that will dig extensive burrows and tunnels with chambers for food storage, nesting and sleeping. Heart Rate: 350 beats/min -> 15 beats/min Respiratory Change: 60 breaths/min -> 20 breaths/min
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