Overwintering is the process by which some

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fu ...

s pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero

temperatures Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on ...

, ice,

snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughou ...

, limited food supplies) make normal activity or even survival difficult or near impossible. In some cases "winter" is characterized not necessarily by cold but by dry conditions; passing through such periods could likewise be called overwintering.

Hibernation Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It mos ...

and

migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

are the two major ways in which overwintering is accomplished. Animals may also go into a state of reduced physiological activity known as

torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the time ...

. Overwintering occurs in several classes of lifeform.

Insects

entomology Entomology () is the scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as ara ...

, overwintering is how an

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

passes the winter season. Many insects overwinter as adults, pupae, or eggs. This can be done inside buildings, under tree bark, or beneath fallen leaves or other plant matter on the ground, among other places. All such overwintering sites shield the insect from adverse conditions associated with winter. Activity almost completely ceases until conditions become more favourable. One example is the mourning cloak butterfly, which experiences advantages to overwintering in its desired locations by being one of the first butterflies to emerge after a cold winter. Another example are the eggs of the forest tent caterpillar moth which overwinter tightly packed on tree branches. Other insects, such as the

monarch butterfly The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. ...

, migrate and overwinter in warmer areas. Additionally, the

ghost moth The ghost moth or ghost swift (''Hepialus humuli'') is a moth of the family Hepialidae. It is common throughout Europe, except for in the far south-east. Female ghost moths are larger than males, and exhibit sexual dimorphism with their differ ...

overwinters as a larva. The

common brimstone ''Gonepteryx rhamni'' (known as the common brimstone) is a butterfly of the family Pieridae. It lives throughout the Palearctic zone and is commonly found across Europe, Asia, and North Africa. Across much of its range, it is the only species ...

, found across a broad geographic range, overwinters for 7 months to wait for the development of their larval host plants. Another unique butterfly, the

large white ''Pieris brassicae'', the large white, also called cabbage butterfly, cabbage white, cabbage moth (erroneously), or in India the large cabbage white, is a butterfly in the family Pieridae. It is a close relative of the small white, ''Pieris ra ...

, will only overwinter in southern Eurasia; they are not seen overwintering elsewhere. Some species of parasitic conopid flies, such as '' P. tibialis,'' are known to overwinter inside of the corpse of their bee/wasp hosts before emerging in the Spring. The queens of the yellow-faced bumblebee (''Bombus vosnesenskii'') will over-winter, and then emerge early in the flight season to obtain the best available subterranean nests. Lastly, many species of ''Lasioglossum'', including '' L. hemichalceum'' (which is a common sweat bee), will overwinter in underground nests before emerging in the spring to start new colonies.

Birds

Many

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s migrate and then overwinter in regions where temperatures are warmer or food is more readily available. Some birds, however, such as

black-capped chickadees The black-capped chickadee (''Poecile atricapillus'') is a small, non-migratory, North American songbird that lives in deciduous and mixed forests. It is a passerine bird in the tit family, the Paridae. It is the state bird of Massachusetts and ...

, Golden-crowned kinglets,

woodpeckers Woodpeckers are part of the bird family Picidae, which also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme polar regions ...

, and corvids, instead remain in colder areas throughout the winter, often remaining in groups for warmth.

Plants

Plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...

s are sometimes said to overwinter. At such times, growth of vegetative tissues and reproductive structures becomes minimal or ceases completely. For plants, overwintering often involves restricted water supplies and reduced light exposure. In the spring following overwintering many plants will enter their flowering stage. Farmers and gardeners use a process of "overwintering" to achieve early spring harvests of some crops by planting annual or biennial species in fall, often under the protection of high or low tunnels. In

plant pathology Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, ...

, overwintering is where a plant pathogen survives the winter, during which its normal

crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydropon ...

host species is not growing, by transferring to an alternative host, living freely in the soil or surviving on plant refuse such as discarded potatoes.

People

People are also described from time to time as overwintering. This was especially true in the past during the exploration of the planet when people had to pass the winter in places not ideally suited for winter survival, and even today in the

polar region The polar regions, also called the frigid zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles. These high latitudes are dominated by flo ...

s. Today people may be said to overwinter when they temporarily move to warmer areas during the months of prevailing cold weather in northern latitudes, such as people from various parts of North America staying in

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...

, Arizona, or New Mexico (among other places) for parts of November to March.

References

{{Reflist Physiology Winter phenomena