# Swamp rabbit

The swamp rabbit (Sylvilagus aquaticus), also known as the cane-cutter, swamper, or cane jake, is a large cottontail rabbit found in the swamps and wetlands of the southern United States. The species is herbivorous, territorial, and nocturnal. When threatened, it will take to the water and swim.

## Taxonomy and etymology

The swamp rabbit was first described in 1874 by John Bachman as Lepus aquaticus, having a type locality of "western Alabama". Other common names of the swamp rabbit are "cane-cutter", "swamper", and "cane jake".
Two subspecies are recognized: Sylvilagus aquaticus aquaticus, the nominate subspecies that occupies most of the swamp rabbit's recognized distribution, and Sylvilagus aquaticus littoralis, which is found only in a narrow band of marshes in Mississippi, Louisiana, and Texas along the Gulf of Mexico coast.

### Fossil record

Sylvilagus aquaticus fossils have been identified as early as the Pleistocene epoch, according to a 1940 discovery of molar teeth found in a Missouri deposit dating back to that era. Glaciations during the Illinoian stage likely created refugia that led to the emergence of the swamp rabbit as a distinct species. The Last Glacial Period following the Pleistocene created a hybrid zone in western Georgia, which likely led to the separation of the swamp rabbit from the marsh rabbit (Sylvilagus palustris), its closest relative.

## Range and habitat

The swamp rabbit is found in much of the south-central United States and along the Gulf coast. It is most abundant in Alabama, Mississippi, and Louisiana, but also inhabits South Carolina, Arkansas, Tennessee, Texas, Oklahoma, Missouri, Kentucky, Illinois, Indiana, and Georgia. It is possibly extirpated from Kansas.
Swamp rabbits mainly live close to lowland water, often in cypress swamps, marshland, floodplain, and river tributaries. Swamp rabbits spend much of their time in depressions which they dig in tall grass or leaves, providing cover while they wait until the nighttime to forage. The swamp rabbit's habitat is shared by many other species, and it has thus been suggested for use as an indicator species.
There is concern that swamp rabbits are increasingly becoming exposed to predation, especially during snowy/wintry seasons. Snow cover has shown to increase swamp rabbit mortality by almost two times in the northern extent of their range. This is due mostly to the fact that snow cover constrains hiding ability and availability of food resources.

## Characteristics

Sylvilagus aquaticus is the largest of the cottontail species, although its ears are smaller than those of other cottontails. Males are slightly larger than females. The head and back are typically dark or rusty brown or black, while the throat, ventral surface, and tail are white, and there is a cinnamon-colored ring around the eye. While largely similar to eastern cottontails (Sylvilagus floridanus) in appearance, the swamp rabbit differs in the sizes of its ears and skull; the former are much smaller, and the latter is larger. Additionally, the back portions of the swamp rabbit's hind legs are orange, in contrast to the tan or white feet of the eastern cottontail.
Sylvilagus aquaticus males vary in weight from approximately 4 lb (1.8 kg) to 5.6 lb (2.5 kg), with an average of about 5 lb (2.3 kg); females vary from approx. 3.6 lb (1.6 kg) to 5.9 lb (2.7 kg), averaging about 4.8 lb (2.2 kg). S. aquaticus ranges in length from approx. 17.8 inches (45 cm) to 21.7 in (55 cm), with an average length of about 19.7 in (50 cm). Males and females of the species show very little sexual dimorphism in regards to size.

## Ecology and behavior

Swamp rabbits are territorial, in contrast to other cottontail rabbits, though they will tolerate some overlap between the home ranges of individuals. These home ranges can vary in size from 1 to 12 hectares. They will mark their territory by "chinning", or marking objects with pheromones produced from glands near the chin. This behavior is also noted in the European rabbit. Rival males may engage in aggressive encounters that sometimes become violent enough to kill one of the combatants. When fighting, males will stand on their hind legs and use their teeth and claws to inflict wounds on their opponent. They will also jump from the ground and strike with the sharp claws of the hind feet. However, compared to nonviolent displays of dominance and submission, fighting is rare.
Swamp rabbits maintain social order through displays of dominance, and communicate directly through vocalizations such as squeaks, chirps, squeals and alert calls. Higher-ranking males will display dominance over lower-ranking males more frequently, and will move within the home ranges of females more frequently, with the alpha male copulating most often in a given season. When escaping, swamp rabbits will dive into water and swim, sometimes keeping only the nose and eyes above the water.

### Diet

Swamp rabbits are herbivorous; they eat a variety of foraged plants, including grasses, sedges, shrubs, tree bark seedlings, and twigs. They feed mainly at night but rain showers will often cause them to feed during daytime as well. A study has found that the preferred foods of S. aquaticus are savannah panicgrass (Panicum gymnocarpum), false nettle (Boehmeria cylindrica), dewberry (Rubus trivialis) and greenbrier (Smilax bona-nox).
Like all lagomorphs, the swamp rabbit creates, expels and eats cecotropes to get more nutrition from its food.

### Reproduction

Swamp rabbits are synchronous breeders. Females give birth to altricial young. Young are born with well-developed fur but their eyes are closed and they are immobile. Their eyes have opened by day three and the young have begun walking. They are weaned and leave the nest after about 15 days. Young are sexually mature at seven months and reach adult weight at 10 months. The nests in which the young are born consist of a slight depression in the earth that is filled with grasses mixed with rabbit hair. These nests, also used for thermoregulation, are known as forms and are common among the non-burrowing species of rabbit.
Breeding season varies widely across the range of Sylvilagus aquaticus, usually occurring anywhere between February and August, but can occur year-round in Texas. Spermatogenesis has been noted to occur in S. aquaticus in Missouri in October and November. In a Mississippi study, groups of males harvested in December and February had higher percentages of individuals with descended testes than those harvested in any other months. S. aquaticus exhibit induced ovulation and have an hour-long estrus. The gestation period lasts 35 to 40 days. Females can have one to three litters a year with each litter consisting of four to six young. The occurrence of embryo resorption has been seen in S. aquaticus; this loss of in-utero litters is attributed to some type of habitat disturbance such as flooding, which may cause overcrowding to occur, as well as directly inducing the release of stress hormones. The swamp rabbit has a diploid chromosome number of 38, similar to the marsh rabbit (Sylvilagus palustris).

### Predation and parasites

Known predators of Sylvilagus aquaticus are domestic dogs (Canis familiaris), American alligators (Alligator mississippiensis), and humans (Homo sapiens). Feral pigs are also a potential predator. Even though their swimming abilities lack the speed to escape a pack of hunting dogs, swamp rabbits elude pursuers by lying still in the water surrounded by brush or plant debris with only their nose visible. The species is hunted for fur, meat, and sport, and is the second-most commonly hunted rabbit in the United States. Swamp rabbits have several adaptations to avoid predators: cryptic coloration, "freezing", and rapid, irregular jumping patterns.
Sylvilagus aquaticus is susceptible to parasitism from various roundworms in the genus Brugia, specifically B. lepori, which is endemic to Louisiana. The roundworms live in the subcutaneous and lymphatic tissue of the rabbit. B. lepori is also known to affect the eastern cottontail, and is suspected as an agent of human Brugia infections in the northeastern United States. S. aquaticus is also affected by other internal parasites, including trematodes and cestodes, as well as the parasitic tick Haemaphysalis leporispalustris.

## Relationship with humans

Of the cottontail rabbits, the swamp rabbit is one of the least studied species. It has an average lifespan of 1.8 years, but individuals living up to 9 years have been recorded. The rabbit is hunted in its native range, both for its products (meat and fur) and for sport, which has been noted as not significantly affecting populations. Agricultural development within its range has caused habitat loss, as these developments both alter the usable habitat and increase severity and frequency of flooding.

### Conservation

Sylvilagus palustris is protected by state-level regulations in some areas. In Indiana, it is classified as "State Endangered", and in Missouri and South Carolina, it is a Species of Special Concern. The International Union for Conservation of Nature considers it a least-concern species as of 2019.