Red Squirrel Biology
Red squirrels can be easily identified from other Grey squirrels by their smaller size, territorial behavior and reddish fur with a white under-belly. Red squirrels are also somewhat larger than Chipmunks.
Red Squirrels are widely distributed across North America preferring to live in conifer/pine tree stands. Their range includes most of Canada, and extends into the United States in the Rocky Mountains, the North Central and North East. However, in New Jersey it is rather rare to encounter a Red Squirrel.
Red Squirrels are primarily granivores, but incorporate other food items into their diet opportunistically. They have been observed eating spruce buds and needles, mushrooms, willow leaves, poplar buds, flowers and berries, and animal material such as bird eggs.
Red Squirrels are spontaneous ovulators. Females enter estrus for only one day, but venture from their territory prior to ovulation and these exploratory forays may serve to advertise their upcoming estrus. On the day of estrus, females are chased by several males in an extended mating chase. Males compete with one another for the opportunity to mate with the estrous female. Estrous females will mate with 4–16 males. Gestation has been reported to range from 31 to 35 days. Females can breed for the first time at one year of age but some females delay breeding until two years of age or older. Most females produce only one litter, but in some years reproduction is skipped while in other years some females attempted to breed twice. Litter sizes typically range from 1 to 5, but most litters contain 3 or 4 offspring. Offspring are pink and hairless at birth and weigh approximately 10 g. Offspring grow at approximately 1.8 g/day while nursing but do not reach adult body size until 125 days of age. Offspring first emerge from their natal nest at around 42 days of age but continue to nurse until approximately 70 days.
Nests are most commonly constructed of grass in the branches of spruce trees. Each individual squirrel has several nests within its territory and females with young move offspring between nests. Some behavior has been reported within human dwellings using insulation as nesting material.
Juvenile Red Squirrels must acquire a territory prior to their first winter. Offspring can acquire a territory by competing for a vacant territory, creating a new territory or by receiving all or part of a territory from their mother.
Red Squirrels experience severe early mortality (on average only 22% survive to one year of age). The survival probability, however, increases to age three at which point it begins to decrease again. Females that survive to one year of age have a life expectancy of 2.3 years and a maximum lifespan of eight years.
The nuisance concerns associated with the Red squirrels are the same as those associated with both the Grey and Flying Squirrels.