Rabbits generally live 12 to 15 months, and only about 1 rabbit in 100 lives through 3 years. Typically, individuals produce 2 to 3 litters per year in northern parts of the range, and 5 to 6 in southern areas.
In the north, first litters are born as early as late March or April, while in the south, litters may be born year-round. Size of litters varies with latitude: rabbits produce 5 to 6 young per litter in the north and 2 to 3 per litter in the south. Gestation is 28 or 29 days and females usually breed again within a few hours of giving birth. Young cottontails are born nearly furless with their eyes closed. The eyes open in 7 to 8 days, they leave the nest in 2 to 3 weeks, and they reach sexual maturity in less than 6 months.
In good conditions, each pair of cottontails can produce about 18 young during the breeding season. Weather, disease, predators, encounters with cars and hunters, and other mortality factors, however, combine to control populations of rabbits. The number of individuals in a given population may change seasonally. Spikes in numbers occur in the spring and summer followed by significant declines in winter. No lethal control is effective for long periods of time because of the reproductive potential of cottontails.
Cottontails do not dig burrows, but rather use natural cavities or burrows excavated by other animals. Dens that are underground are used primarily in extremely cold or wet weather, or to escape from predators. Piles of brush and other cover often are used as alternatives to burrows.
In spring and fall, rabbits use a shelter made from grass or weeds, which is called a “form.” The form is a cavity on the surface of the ground, usually made in dense cover. It gives rabbits some protection from weather but is largely used for concealment. In summer, lush green growth provides both food and shelter, leaving little need for a form. Rabbits give birth in a shallow nest depression in the ground.
Cottontails are not distributed evenly across a landscape. They tend to concentrate in favorable habitats such as brushy fence rows, edges of fields, gullies filled with debris, piles of brush, and backyards with extensive landscaping. They rarely are found in dense forests or open grasslands. Fallow crop fields may provide suitable habitat.
Cottontails generally spend their entire lives in an area of 10 acres or less, but they may move a mile or so from summer to winter range, or to a new food supply. Lack of food or cover usually motivates a rabbit to move to another area. In suburban areas, rabbits are numerous and mobile enough to fill any open habitat that is created when other rabbits are removed. Density of populations varies with habitat quality, but 1 rabbit per acre is a reasonable average.
Rabbits eat flowers (e.g., tulips) and vegetables (e.g., peas, beans, and beets) in spring and summer. In fall and winter, they damage and kill valuable woody trees and shrubs by clipping and gnawing the bark (Figure 7), particularly when snowfall is heavy. Crops, such as corn, squash, cucumbers, tomatoes, potatoes, and some peppers, seem to be immune from damage by rabbits. Preferences for types of food vary considerably by region and season. In general, cottontails seem to prefer plants in the rose family. Apple trees, black and red raspberries, and blackberries are the most frequently damaged food-producing woody plants, although cherry, plum, and nut trees also may be damaged.