Eastern Cottontail Rabbit
| Scientific Name | Sylvilagus floridanus |
| Survival Strategy | Active All Winter |
| Conservation Status | Least Concern |
Spring
Breeding, which began in late winter, continues into spring, with the first litter being born in late March or early April. The leafy greens of spring become available around the time when a nursing cottontail doe needs extra nutrition. The spring molt begins in mid-April as cottontails swap their warm winter coat for something lighter for the summer.
Summer
Cottontail rabbits have their second litter by early summer. Their diet consists primarily of tender plants and garden crops.
Fall
A possible third litter arrives in September. As fall progresses, the available food transitions from the green plants of summer to woody stems and buds. Cottontails begin building the layer of brown fat needed to survive the winter. By mid-September, rabbits go through a fall molt and develop a warmer coat for winter.
Winter
In the colder months, the only food available is the less-nutritious high-cellulose stems and buds that provide less energy than the rabbit uses each day, so they must rely on their brown fat for energy. Breeding begins in February and continues to September.
Behavior
Winter Shelter
Cottontail rabbits look for shelter as cold weather sets in, preferably near a reliable food source. A quality refuge covered by a blanket of insulating snow is an ideal place to ride out a storm in severe weather. Dense shrubs, stands of conifers, and brush piles make prime rabbit shelters. Cottontails do not dig dens but will use abandoned fox or badger dens as protection from low temperatures. Rabbits may also take shelter under a deck or chicken coop. If you see a narrow snow-packed trail with a few scattered “cocoa puffs” here and there, it will likely lead to a cottontail rabbits winter shelter.
Physiology
Reproduction
Cottontail rabbits are polygamous, with mating beginning late winter and continuing until fall. The average litter size is five kits (baby rabbits) which are born altricial; they are entirely dependent on the care of their mother. The doe mates within days after giving birth. The kits are weaned in three weeks, independent after seven weeks, and reach sexual maturity in three months. The female will produce 2 or 3 litters each year.
Brown Fat Provides Fuel
In the fall, cottontail rabbits build a layer of brown fat (brown adipose tissue).
In winter, they can generate heat by releasing the energy stored in this brown fat through metabolism. Brown fat has more mitochondria than white fat, and these mitochondria act like fat-burning stoves which produce heat quickly. This layer of fat also serves as extra insulation. The winter diet of the cottontail would not provide enough nutrition to survive a harsh winter in the upper Midwest without the energy stored in brown fat.
The Down Side of Brown Fat
While the metabolism of brown fat creates life-sustaining heat, it also produces free radicals (unstable atoms that damage cells and DNA). Vitamin C can help protect the rabbit from the cell damage caused by these unstable atoms. Rabbits get vitamin C from a summer diet rich in green leafy foods and an enzyme in their liver. The winter diet of a cottontail provides minimal vitamin C when protection from free radicals is needed most. The liver of a cottontail rabbit produces ten times more vitamin C in the winter than in the summer.
Two Types of Number Two
Cottontail rabbits eat leaves, woody stems, bark, and berries. Their ability to transform this cellulose-rich diet into valuable nutrients is key to their winter survival. Like all rabbits, their digestive system produces two types of waste, cecal pellets (soft) and fecal pellets (hard).
After traveling through the small intestine, any food that a rabbit can digest further takes a side trip into the cecum, where bacteria break down the plant material into simple sugars. After leaving the cecum, the food passes through the large intestine and the anus as soft cecal pellets, which the rabbit quickly eats. The bacteria in the cecal pellets provide up to 20% of a cottontail’s daily protein requirement in addition to making vitamin B.
Indigestible fibrous food avoids the cecum and travels directly to the large intestine, where water is absorbed before it passes out of the body as hard fecal pellets. The rabbit typically ignores these pellets unless food is scarce. Rabbits will eat fecal pellets if winter weather makes foraging for food difficult or dangerous. Although not nearly as nutritious as cecal pellets, dry fecal pellets may provide enough energy to prevent starvation.
Coprophagy (eating feces) is common in many other animals such as rats, mice, hamsters, guinea pigs, and chinchillas. Newborn elephants, pandas, hippopotamuses, and koalas are born with sterile digestive systems. By eating their mother’s feces, they obtain the “starter” bacteria needed to digest the vegetation found in their ecosystems.
Diet
The summer diet of eastern cottontails is predominantly tender green plants, including clovers, alfalfa, timothy, ragweed, goldenrods, plantains, and dandelion. They will also eat most anything from a home vegetable or flower garden.
After leafy green plants have been killed by frost and covered with snow, the eastern cottontails diet switches to twigs, buds, and bark of trees and shrubs, including aspen, red maple, and black cherry.
Lifespan and Mortality
The average lifespan of a cottontail rabbit is less than two years, with only about 20% surviving annually.
Predators
Predators of cottontail rabbits include Hawks, owls, red foxes, coyotes, weasels, humans, and dogs.
Disease
Rabbit Haemorrhagic Disease (RHD) is a highly contagious viral disease that attacks wild and domestic rabbits and is nearly always fatal. It only infects rabbits, although other animals (including humans and hunting dogs) can spread the virus through contact.
Climate Vulnerability
A warming climate will likely shift the cottontail rabbit’s range northward, but the range will not change in size.
Never Stop Learning
Invasive Species: The Eastern cottontail is invasive in Central and Northern Italy and British Columbia.
Rabbit vs. Hare: Hares have longer ears and feet, prefer open areas, run from predators, and their young are born precocial. Rabbits have smaller ears and feet, prefer wooded or shrubby areas, hide from predators, and their young are born altricial.
References
| Where Do Wild Rabbits Go in the Winter? by Lou Carter https://www.rabbitcaretips.com/where-wild-rabbits-go-in-winter/ |
| Mikita, K. 1999. “Sylvilagus floridanus” (On-line), Animal Diversity Web. Accessed January 09, 2022 at https://animaldiversity.org/accounts/Sylvilagus_floridanus/ |
| (2001). Coprohagy in leporids and other mammalian herbivores. Mammal Review. https://doi.org/10.1046/j.1365-2907.2001.00079.x |
| Why Do Some Animals Eat Poop? https://youtu.be/Ubt2fl11v5E |
| Thomas, Vernon G. “Similar Winter Energy Strategies of Grouse, Hares and Rabbits in Northern Biomes.” Oikos, vol. 50, no. 2, [Nordic Society Oikos, Wiley], 1987, pp. 206–12, https://doi.org/10.2307/3566002. |
| Leach K, Kelly R, Cameron A, Montgomery WI, Reid N (2015) Expertly Validated Models and Phylogenetically-Controlled Analysis Suggests Responses to Climate Change Are Related to Species Traits in the Order Lagomorpha. PLoS ONE 10(4): e0122267. https://doi.org/10.1371/journal.pone.0122267 |
| Abrantes, J., van der Loo, W., Le Pendu, J. et al. Rabbit haemorrhagic disease (RHD) and rabbit haemorrhagic disease virus (RHDV): a review. Vet Res 43, 12 (2012). https://doi.org/10.1186/1297-9716-43-12 |
| Rabbit Hemorrhagic Disease Fact Sheet https://cwhl.vet.cornell.edu/system/files/public/cwhl-fact-sheetsrhdv.pdf |