Wildlife Wednesday -- Swamp Rabbit (Sylvilagus aquaticus)

The Swamp Rabbit (Sylvilagus aquaticus), also known as the cane cutter, Watership, swamper, or cane jake, is a species of cottontail rabbit found in the swamps and wetlands of the southern United States. It is herbivorous, territorial, and nocturnal. The largest of the cottontail rabbits, it is similar in appearance to the Eastern Cottontail, but has distinctly smaller ears and orange-colored hind legs. And, it will be the subject of Wildlife Wednesday at 12 p.m. on Wednesday, Oct. 7, in the Nature Center at Jesse Jones Park.
Its habitat is largely dominated by regions near lowland water. Unlike other cottontail rabbits, the Swamp Rabbit is territorial and maintains a social order between higher- and lower-ranking males and females via displays of dominance, vocalizations, and occasional fighting. This rabbit is unique in that it ventures into water on its own, unlike other Texas rabbits, and is rarely spotted during the day due to its secretive nature. When threatened, it will take to water and swim. Swamp Rabbits in a given population usually breed around the same time, giving birth to young that are born blind, immobile, and completely dependent for the first few days. Their nests — called forms — are lined with fur and grass. Each litter produces one to six young. The breeding season varies across the species' range: In Texas, the breeding season lasts all year, but elsewhere occurs between February and August.
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 (locally extinct) 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 has been suggested for use as an indicator species, as its preferred habitat is shared by many other species, the rabbit makes use of different aspects of its habitat, and monitoring is easy to do. The ranges of both the Marsh Rabbit and Eastern Cottontail overlap with that of the Swamp Rabbit.
Sylvilagus aquaticus is the largest of the cottontail species, although its ears are smaller than those of other cottontails, being medium-sized with relation to the rest of its body. The head and back are typically dark or rusty brown or black
Swamp Rabbits are territorial, though they will tolerate some overlap between the home ranges of individuals depending on the season. These home ranges can vary in size from 2.5-29.7 acres. They will mark their territory by "chinning"— marking objects with pheromones produced from glands near the chin. This behavior is also noted in the European Rabbit. Males that are competing for territory or status may fight, with battles sometimes resulting in the death of an individual. Males will stand up on their hind legs, lashing out with their teeth and claws, and will even use the claws on their hind feet in jumping attacks. 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. The system of male dominance prevents injury between subordinate breeding males under the alpha, as the lower-ranking individuals will avoid higher-ranking males to prevent conflict. When escaping, Swamp Rabbits will use confusing maneuvers to evade a pursuer, such as jumping onto a log, running to the end, then backtracking and jumping off the other side. They are excellent swimmers, and may also dive into water to escape, sometimes keeping only the nose and eyes above the water.
Swamp Rabbits are herbivorous; they eat a variety of foraged plants, including grasses, sedges such as Carex, shrubs, tree bark seedlings, and twigs. Though mostly nocturnal, the Swamp Rabbit may emerge during rain showers to feed during the day. 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 (rabbits, hares, and pikas), the Swamp Rabbit performs cecotrophy to get more nutrition from its food. In this process, food passes through the digestive tract twice, as the Swamp Rabbit will immediately consume moist pellets expelled from the anus without chewing and leave behind the dry pellets that are subsequently produced. This process is considered similar to the cud-chewing behavior of ruminants.
Swamp Rabbits are synchronous breeders, and tend to breed all at the same time within a population. Females will line a depression in the ground with fur and grass to form a birthing nest. These nests, also used for thermoregulation, are known as forms and are common among the non-burrowing species of rabbit. Females give birth to altricial young — they are immobile upon birth, and only open their eyes and walk after three days. Weaning ends at 15 days, at which point the young leave the nest. They become sexually mature at seven months and reach their adult weight at 10 months. Little is known about the recruitment behavior of juveniles into larger groups.
The Swamp Rabbit's breeding season varies across its range. It occurs year-round in Texas, but elsewhere may take place between February and August. Spermatogenesis occurs in October and November according to a Missouri study, and in Mississippi, recorded males had descended testes more often in December and February than in any other months. Estrus lasts one hour following induced ovulation. Gestation lasts 37 days on average. Up to three litters are produced annually, with each litter producing one to six young. Embryo resorption can occur in S. aquaticus in response to stress, causing loss of litters. This is attributed to flooding, which can cause overcrowding as well as directly inducing the release of stress hormones.
Known predators of Sylvilagus aquaticus are domestic dogs, American alligators, and humans. Feral pigs are also a potential predator. The Swamp Rabbit cannot swim fast enough to escape hunting dogs, and so will attempt to escape pursuers by hiding under water among plants and brush with only its nose above the surface. 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.
The Swamp Rabbit has an average lifespan of 1.8 years, but individuals living up to 9 years have been recorded. It 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. The Swamp Rabbit is occasionally kept in captivity as a subject of study.
To learn more about this common resident of Jesse Jones Park, come to Wildlife Wednesday on October 7 at 12 p.m. in the Nature Center. The program is free of charge and open to rabbit lovers of all ages.