Several different species of squirrels live in North America. Because all squirrels are mammals, their reproduction behaviors are somewhat similar, but issues of gestation, litter size and mating can vary from species to species. To understand the similarities and differences between squirrel species, we can compare several of their gestation and mating habits. These species include fox, flying, red, gray, and ground squirrels.
Fox squirrels are a type of tree squirrel that lives in the central and eastern United States, as well as in Canada and Mexico. Males and females of the species breed year-round with males competing to determine which ones get to mate first. Females can also mate with multiple partners during one breeding period. After conception occurs, gestation usually lasts 45 days. On average, mother squirrels welcome two to three babies, but she can have up to seven babies in a single litter. Typically, only one litter of babies is born to a mother fox squirrel per year. Two is the maximum possible.
Like the fox squirrel, flying squirrels are found throughout the eastern United States, southern parts of Canada, and in Central America. Although flying squirrels are common, not much research has been done on the interactions between males and females, so little is known about their mating habits. What researchers do know is that mating happens twice each year, usually in early spring and late summer. Gestation lasts about 40 days then mother flying squirrels give birth to two to three babies, on average.
For red squirrels, mating must take place quickly because the females are only fertile one day each breeding season (each season lasts 105 days). A dominant male will chase the female, then will copulate with her multiple times to ensure breeding success. Conception occurs almost immediately after mating and gestation only lasts 35 days. Red squirrels typically have two litters per year, but in the northernmost parts of their territory (which covers most of North America) they may have only one per year. Litters can contain up to eight babies, but most mother red squirrels have four.
Along the eastern coasts of North America and Canada, the gray squirrel's mating ritual shares some similarities to that of the red squirrel. When a female is nearing her period of fertility, a group of up to 10 males will begin chasing her. Usually, the most dominant of the males will end up earning the right to mate with her after a brief period of courtship. These breeding periods occur twice each year, usually in the middle of summer and again near the end of winter. After successful mating occurs, gestation lasts about 44 days. Gray squirrel litters can include up to nine babies, but the average litter includes only two or three.
The ground squirrel mates only once per year. The mating season begins just after hibernation ends and usually only lasts a few weeks. During that time males and females can mate with multiple partners. In fact, a single litter of babies may have different fathers. Gestation for ground squirrels lasts between 25 and 30 days. Litters can be quite large (up to 15 babies per litter), but the average size is only seven or eight babies. Of these, only five or six are likely to survive to maturity.
- Squirrel World: Species of Squirrels
- Animal Diversity Web: Easter Fox Squirrel
- Indiana Department of Natural Resources: Fox Squirrel
- Animal Diversity Web: Southern Flying Squirrel
- Animal Diversity Web: Red Squirrel
- Clemson Cooperative Extension: Gray Squirrel Biology and Management
- Adirondack Ecological Center: Gray Squirrel
- University of California: Ground Squirrel Breeding
- Animal Diversity Web: California Ground Squirrel
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