Squirrels, belonging to the rodent family Squirrel family, refers to a large class of rodents with fluffy long hairs on their tails, with about 58 genera and 285 species in existence, distributed throughout all continents outside Antarctica (introduced species in Oceania).
<h3>Rhythms of behavior</h3>
Squirrels are active all year round, do not hibernate, are day-to-day animals, and the daily start time of activity is related to sunrise time, while the end activity time is not significantly related to sunset time. The daily activity rhythm of squirrels is affected by climatic conditions, and high winds, heavy rainstorms and severe cold and heat will reduce the activity time of squirrels. The tradeoff between the need for foraging and staying in the nest to conserve energy affects the winter activity pattern of squirrels. In winter, the daily activity rhythm is monomodal, and it will remain in the nest for several days in severe cold weather conditions. In summer, there is a peak in activity in the morning and afternoon. The pattern of daily activity in spring and autumn is between winter and summer.
<h3>Feeding behavior</h3>
Squirrels spend 70% to 80% of their time foraging activities, tending to forage and store in coniferous forests. Autumn squirrels scatter nuts on the ground and fungi on branches. Autumn storage is conducive to squirrel overwintering and second-year fertility. The selection of micro-habitats and the mechanism of re-extraction of squirrel storage have been deeply studied, and have become the hot spots of domestic squirrel ecology research.
<h3>Community Behavior</h3>
Squirrels live alone most of the time. Community structures are based on sequences of dominance between the same sexes and between the sexes, and the dominant individuals are usually larger than other individuals. Hierarchical advantages are usually only manifested during the reproductive season. Squirrels use urine and secretions from the mandibular glands to smear on trunks and branches to mark home ranges. The size of the squirrel's home area is related to habitat quality, season, sexual activity and food abundance, and the size of the home area varies greatly in different distribution areas, but usually the male home area is larger than the female, and the dominant individual home area is larger than that of the secondary individual. In food-rich areas, small overlaps occur in the home area.
<h3>Nesting behavior</h3>
Squirrel camp nesting life, you can also use tree holes and bird nests. Each individual usually occupies 2 to 3 nests at the same time. Since the branches and leaves of the fir trees are denser than those of pine trees, in plantations, squirrels usually choose to nest on the fir trees. Nest site selection in natural forests has not been reported. Most of the nests are built on branches 8 to 16 m above the ground, near the trunk or at the fork of the branches, divided into two types of rest nests used during the day and sleep nests used at night, usually spherical in shape, about 30 cm in diameter, the outer layer is made of twigs, pine needles and leaves, the inner diameter is about 12 to 16 cm, covered with soft materials such as moss, leaves, pine needles, hay and bark. In the winter, a microclimate environment is formed in the nest of squirrels, and the temperature can be 20 to 30 ° C higher than that outside the nest, thereby reducing the energy consumed by the body's body temperature regulation and reducing the time exposed to low temperatures and winds outside the nest, which is one of the winter survival strategies of squirrels living in the northern temperate region. In the cold winter, there will also be several squirrels sharing the same nest to maintain body temperature.
<h3>Reproductive behavior</h3>
The reproductive status of squirrels is closely related to the status of food acquisition. It is possible to have two births per year, mating in February, March and July and August, with a gestation period of about 38 to 39 days. But if food is not available, spring mating can be delayed or disappeared. The marriage system is a one-male poly-female system or a mixed mating system. There is courtship behavior before mating, and usually the dominant male will have more mating opportunities. Newborn female rats usually begin to give birth in the second year, and their reproductive ability is closely related to body weight, only female squirrels that exceed a certain weight threshold have fertility, and the larger the weight, the more offspring can be produced. The pups are fed alone by female rats for a period of more than 10 weeks of lactation.
<h3>Migration and diffusion</h3>
Squirrels do not migrate significantly, but have short-range spread behavior, including outward spread from the wintering ground and outward from the place of birth. Local competition determines the current status of population squirrel ecology and the prospective diffusion distance. Studies have shown that different sexes differ in the spread season, with most male individuals spreading in the spring, while females usually spread in the fall. The spread of female individuals is affected by food, while the spread of males depends on the distribution of females.
Contributors to this entry are: Yufeng Liu - Associate Professor - Liaoning University
This article was co-edited by Toutiao Users Adaptive Scrawling, y77889900, Niceeeeeday, and Science Popularization China.