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Swamp rabbit

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Swamp rabbit[1]
Temporal range: Pleistocene–recent[2]
0.126–0 Ma
↓
A photograph of a swamp rabbit in the grass taken from the side, with the rabbit's head facing towards the camera
Sylvilagus aquaticus in Baton Rouge, Louisiana, United States
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Lagomorpha
Family: Leporidae
Genus: Sylvilagus
Species:
S. aquaticus
Binomial name
Sylvilagus aquaticus
(Bachman, 1837)
Swamp rabbit range
Synonyms[4]
List
    • Lepus aquaticus attwateri J. A. Allen, 1895
    • Lepus aquaticus Bachman, 1837
    • Lepus telmalemonus D. G. Elliot, 1899
    • Limnolagus aquaticus Lyon, 1904
    • Limnolagus aquaticus attwateri Lyon, 1904
    • Limnolagus telmalemonus Lyon, 1904
    • Sylvilagus aquaticus Corbet & J. Edwards Hill, 1980
    • Sylvilagus aquaticus littoralis E. W. Nelson, 1909
    • Sylvilagus aquaticus aquaticus R. S. Hoffmann & A. T. Smith, 2005

The swamp rabbit (Sylvilagus aquaticus), also known as the cane-cutter, swamper, or cane jake, is a species of mammal in the family Leporidae found in the swamps and wetlands of the southern United States. The species 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. Known since the 19th century, the swamp rabbit was first described with the scientific name of Lepus aquaticus by John Bachman in 1837; it was moved to the genus Limnolagus in 1904, and later to Sylvilagus in 1909. It is closely related to the marsh rabbit. The two species likely separated during the Last Glacial Maximum.

The swamp rabbit is most abundant in Alabama, Mississippi, and Louisiana, and also inhabits South Carolina, Arkansas, Tennessee, Texas, Oklahoma, Missouri, Kentucky, Illinois, Indiana, Georgia. 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. When threatened, it will take to water and swim. Swamp rabbits are synchronous breeders and give birth to altricial young in fur- and grass-lined nests known as forms. Each litter produces four 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.

Predators, parasites, and human interaction pose threats to the swamp rabbit. Dogs, American alligators, and feral pigs prey upon the swamp rabbit, and it is a potential host to several roundworms, trematodes, and the rabbit tick. The swamp rabbit is also affected by tularemia. It is hunted for its meat and fur, and faces habitat loss due to expansion of agricultural developments that both remove usable habitat and cause frequent flooding. The International Union for Conservation of Nature lists it as a least-concern species, but in some states it is protected as a vulnerable or special concern species.

Taxonomy and etymology

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Illustration of a swamp rabbit labeled "swamp hare"
John James Audubon's 1851 illustration of a male "swamp hare"

The swamp rabbit was first described in 1837 by John Bachman as Lepus aquaticus, having a type locality of "western Alabama".[5] In 1904, it was placed in the genus Limnolagus as the type species by Marcus Ward Lyon Jr.; the name was previously used as the subgenus of both the swamp rabbit and marsh rabbit (S. palustris) in an 1899 work by Charles Immanuel Forsyth Major.[6] Edward William Nelson clarified several years later in 1909 that the species belonged to Sylvilagus and grouped it alongside the marsh rabbit.[7] Common names of the swamp rabbit include "cane-cutter", "swamper", and "cane jake".[8]

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.[8] Nelson made the distinction between the subspecies in the same 1909 work where the species was classified as a member of Sylvilagus, noting that the littoralis form had "remarkable" differences from the nominate subspecies and that it had been assumed to be the "true aquaticus" in prior studies.[7]

Fossil record

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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.[5] 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 (S. palustris), its closest relative.[8]

Phylogeny

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The swamp rabbit has 38 diploid chromosomes,[9][10] the same number as the marsh rabbit[11] and fewer than several other members of Sylvilagus.[12][13] Based on mitochondrial and nuclear gene analysis, its closest genetic relative is the marsh rabbit, with which it forms a clade. Its next closest relatives are the desert cottontail (S. audubonii) and mountain cottontail (S. nuttallii).[14]

Range and habitat

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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.[15] It is possibly extirpated from Kansas.[16]

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.[15] The swamp rabbit's habitat is shared by many other species, and it has thus been suggested for use as an indicator species.[17] The ranges of both the marsh rabbit and eastern cottontail overlap with that of the swamp rabbit.[9]

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.[18]

Characteristics

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A photograph of a swamp rabbit in profile on rocky ground
S. aquaticus in Bluebonnet Swamp Nature Center

Sylvilagus aquaticus is the largest of the cottontail species,[19] although its ears are smaller than those of other cottontails, being medium-sized with relation to the rest of its body.[9] 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.[15] While largely similar to eastern cottontails (S. 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.[8]

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).[15] Males and females of the species show very little sexual dimorphism in regards to size.[20]

Ecology and behavior

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A photograph of a rabbit standing on its hind legs grooming in the grass near a fence
Swamp rabbit grooming itself

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.[8] 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.[5] 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.[21] However, compared to nonviolent displays of dominance and submission, fighting is rare.[8]

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.[8]

Diet

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Swamp rabbits are herbivorous; they eat a variety of foraged plants, including grasses, sedges such as Carex,[9] shrubs, tree bark seedlings, and twigs.[15] Though mostly nocturnal, the swamp rabbit may emerge during rain showers to feed during the day.[21] The preferred foods of S. aquaticus are savannah panicgrass (Panicum gymnocarpum), false nettle (Boehmeria cylindrica), dewberry (Rubus trivialis) and greenbrier (Smilax bona-nox).[15]

Like all lagomorphs, the swamp rabbit creates, expels and eats cecotropes to get more nutrition from its food.[15]

Reproduction

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Swamp rabbits are synchronous breeders. Females give birth to altricial young. The young are immobile upon birth, only opening their eyes and walking after 3 days. Weaning ends at 15 days, at which point the young leave the nest. They become sexually mature at 7 months and reach their adult weight at 10 months.[22] Females will line a depression in the ground with fur and grass to form a birthing nest.[21][23] These nests, also used for thermoregulation, are known as forms and are common among the non-burrowing species of rabbit.[24]

A very young swamp rabbit being held in a person's hand
Juvenile swamp rabbit

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.[25] Estrus lasts one hour following induced ovulation. Gestation lasts 37 days on average. Up to three litters are produced annually, with each litter generally consisting of three young.[20] Embryo resorption can occur in S. aquaticus in response to stress, causing loss of litters. This is attributed to flooding, which can cause overcrowding[22] as well as directly inducing the release of stress hormones.[8][10]

Predators, parasites and diseases

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Known predators of Sylvilagus aquaticus are domestic dogs, American alligators, and humans.[15] Feral pigs are also a potential predator.[26] The swamp rabbit cannot swim fast enough to escape hunting dogs,[27] and so will attempt to escape pursuers by hiding under water among plants and brush with only its nose above the surface.[21] 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.[15]

Sylvilagus aquaticus is susceptible to parasitism from various roundworms in the genus Brugia, specifically B. lepori, which is endemic to Louisiana.[28] The roundworms live in the subcutaneous and lymphatic tissue of the rabbit. B. lepori is also known to affect the eastern cottontail,[29] and is suspected as an agent of human Brugia infections in the northeastern United States.[30] S. aquaticus is also affected by other internal parasites, including trematodes and cestodes, as well as the parasitic tick Haemaphysalis leporispalustris.[5] It is known to contract tularemia[8] and leptospirosis, though the latter disease is not considered to have a major impact on mortality.[31]

Relationship with humans

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A rabbit seen on an outdoor porch
A swamp rabbit in St. Tammany Parish, Louisiana

Of the cottontail rabbits, the swamp rabbit is one of the least studied species. It has an average lifespan of 1.8 years,[5] but individuals living up to 9 years have been recorded.[32] 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.[8]

Conservation

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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.[8] The International Union for Conservation of Nature considers it a least-concern species as of 2019, though it notes that the population is decreasing overall.[3]

See also

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References

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  1. ^ Hoffmann, R.S.; Smith, A.T. (2005). "Sylvilagus (Tapeti) aquaticus". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 207–208. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ^ "Sylvilagus aquaticus (swamp rabbit)". Paleobiology Database. Archived from the original on 2025-03-26. Retrieved 2025-03-26.
  3. ^ a b Lanier, H.C.; Nielsen, C. (2019). "Sylvilagus aquaticus". IUCN Red List of Threatened Species. 2019: e.T41296A45190578. doi:10.2305/IUCN.UK.2019-1.RLTS.T41296A45190578.en. Retrieved 19 November 2021.
  4. ^ "Sylvilagus aquaticus (id=1001123)". ASM Mammal Diversity Database. American Society of Mammalogists. Retrieved 31 March 2025.
  5. ^ a b c d e Chapman, Joseph A.; Feldhamer, George A. (1981-05-08). "Sylvilagus aquaticus". Mammalian Species (151): 1–4. doi:10.2307/3504012. JSTOR 3504012.
  6. ^ Lyon, Marcus Ward, Jr. (1904). "Classification of the hares and their allies" (PDF). Smithsonian Miscellaneous Collections. 45 (28): 329–330.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ a b Nelson, Edward William (August 31, 1909), "The rabbits of North America", North American Fauna, 29 (29), United States Department of Agriculture: 265–275, doi:10.3996/nafa.29.0001
  8. ^ a b c d e f g h i j k Nielsen, Clayton K.; Berkman, Leah K. (2018). "Sylvilagus aquaticus (Bachman, 1837) Swamp rabbit". In Smith, Andrew T.; Johnston, Charlotte H.; Alves, Paulo C.; Hackländer, Klaus (eds.). Lagomorphs: Pikas, Rabbits, and Hares of the World. Baltimore: Johns Hopkins University Press. pp. 117–119. doi:10.1353/book.57193. ISBN 978-1-4214-2341-8. LCCN 2017004268.
  9. ^ a b c d Pintus, Kathryn; Bourne, Debra. "Sylvilagus aquaticus - Swamp rabbit". Wildpro. Twycross Zoo. Archived from the original on January 21, 2018. Retrieved 31 March 2025.
  10. ^ a b Robinson, T.J.; Elder, F.F.B.; Chapman, J.A. (2008-05-07). "Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha): S. aquaticus, S. floridanus, and S. transitionalis". Cytogenetics and Cell Genetics. 35 (3): 216–222. doi:10.1159/000131869. ISSN 0301-0171. PMID 6861527.
  11. ^ Robinson, T.J.; Elder, F.F.B.; Chapman, J.A. (2008-05-08). "Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha): II. Sylvilagus audubonii, S. idahoensis, S. nuttallii, and S. palustris". Cytogenetics and Cell Genetics. 38 (4): 282–289. doi:10.1159/000132076. ISSN 0301-0171. PMID 6510022.
  12. ^ Robinson, T.J.; Elder, F.F.B.; Chapman, J.A. (2008-05-07). "Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha): S. aquaticus, S. floridanus, and S. transitionalis". Cytogenetics and Cell Genetics. 35 (3): 216–222. doi:10.1159/000131869. ISSN 0301-0171. PMID 6861527.
  13. ^ Robinson, T.J.; Elder, F.F.B.; Chapman, J.A. (2008-05-08). "Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha): II. Sylvilagus audubonii, S. idahoensis, S. nuttallii, and S. palustris". Cytogenetics and Cell Genetics. 38 (4): 282–289. doi:10.1159/000132076. ISSN 0301-0171. PMID 6510022.
  14. ^ Iraçabal, Leandro; Barbosa, Matheus R.; Selvatti, Alexandre Pedro; Russo, Claudia Augusta de Moraes (2024). "Molecular time estimates for the Lagomorpha diversification". PLOS ONE. 19 (9): e0307380. doi:10.1371/journal.pone.0307380. ISSN 1932-6203. PMC 11379240. PMID 39241029.
  15. ^ a b c d e f g h i Roszko, Annamarie (2007). Dewey, Tanya; Powers, Karen (eds.). "Sylvilagus aquaticus". Animal Diversity Web. University of Michigan Museum of Zoology. Archived from the original on 2013-05-27. Retrieved 26 March 2025.
  16. ^ "Sylvilagus aquaticus". NatureServe Explorer. Archived from the original on 24 October 2022. Retrieved 26 March 2025.
  17. ^ Suriyamongkol, Thanchira; Esposito, Jessica L.; Nielsen, Clayton K.; Groninger, John W. (2024), Effectiveness of swamp rabbits as indicator species for wildlife in bottomland hardwood forests, doi:10.2139/ssrn.4986899, retrieved 2025-02-18
  18. ^ Hillard, Elizabeth M.; Edmund, Alison C.; Crawford, Joanne C.; Nielsen, Clayton K.; Schauber, Eric M.; Groninger, John W. (2018). "Winter Snow Cover Increases Swamp Rabbit (Sylvilagus aquaticus) mortality at the northern extent of their range". Mammalian Biology. 93: 93–96. Bibcode:2018MamBi..93...93H. doi:10.1016/j.mambio.2018.09.001.
  19. ^ Álvarez-Castañeda, Sergio Ticul (2024), "Order Lagomorpha", Mammals of North America - Volume 1, Cham: Springer Nature Switzerland, p. 537, doi:10.1007/978-3-031-41661-3_8, ISBN 978-3-031-41660-6, retrieved 2025-02-24
  20. ^ a b Heldstab, Sandra A. (December 2021). "Habitat characteristics and life history explain reproductive seasonality in lagomorphs". Mammalian Biology. 101 (6): 739–757. doi:10.1007/s42991-021-00127-0. ISSN 1616-5047.
  21. ^ a b c d Reed, Don (September 2008). "Wildlife species profile: Swamp rabbit (Sylvilagus aquaticus)" (PDF). Louisiana Wildlife News. No. 5. Louisiana State University Agricultural Center. Archived (PDF) from the original on 11 December 2014. Retrieved 25 November 2014.
  22. ^ a b Courtney, Emily M. (5 September 2008). "Swamp rabbit (Sylvilagus aquaticus)" (PDF). Mammals in Mississippi. No. 3. Department of Wildlife and Fisheries, Mississippi State University. Archived (PDF) from the original on 23 September 2015. Retrieved 11 December 2014.
  23. ^ Svihla, Ruth Dowell (November 1929). "Habits of Sylvilagus aquaticus littoralis". Journal of Mammalogy. 10 (4): 315–319. doi:10.2307/1374118. JSTOR 1374118.
  24. ^ Milling, Charlotte R.; Rachlow, Janet L.; Johnson, Timothy R.; Forbey, Jennifer S.; Shipley, Lisa A. (2017-09-01). "Seasonal variation in behavioral thermoregulation and predator avoidance in a small mammal". Behavioral Ecology. 28 (5): 1236–1247. doi:10.1093/beheco/arx084. ISSN 1045-2249.
  25. ^ Bond, Bobby T.; Bowman, Jacob L.; Leopold, Bruce D.; Wes Burger, Jr., L.; David Godwin, K.; Class, Corey M. (2006). "Swamp rabbit (Sylvilagus aquaticus) demographics, morphometrics, and reproductive characteristics in Mississippi" (PDF). Journal of the Mississippi Academy of Sciences. 51 (2): 123–128. Retrieved 12 October 2024.
  26. ^ Stevens, Thomas K.; Hale, Amanda M.; Williams, Dean A. (February 2023). "Environmental and anthropogenic variables influence the distribution of a habitat specialist (Sylvilagus aquaticus) in a large urban forest". Conservation Science and Practice. 5 (2). Bibcode:2023ConSP...5E2882S. doi:10.1111/csp2.12882. ISSN 2578-4854.
  27. ^ "This swamp rabbit can swim: Remarkable Rabbits". CBC.ca. Archived from the original on 2019-04-08. Retrieved 2019-04-08.
  28. ^ Evans, Christopher C.; Pilotte, Nils; Moorhead, Andrew R. (2024-08-23). "Current status of the diagnosis of Brugia spp. infections". Pathogens. 13 (9): 714. doi:10.3390/pathogens13090714. ISSN 2076-0817. PMC 11434688. PMID 39338906.
  29. ^ Eberhard, M. L. (August 1984). "Brugia lepori sp. n. (Filarioidea: Onchocercidae) from rabbits (Sylvilagus aquaticus, S. floridanus) in Louisiana". Journal of Parasitology. 70 (4): 576–579. doi:10.2307/3281408. ISSN 0022-3395. JSTOR 3281408. PMID 6502360.
  30. ^ Eberhard, Mark L.; Telford III, Sam R.; Spielman, Andrew (October 1991). "A Brugia species infecting rabbits in the northeastern United States". Journal of Parasitology. 77 (5): 796. doi:10.2307/3282722. JSTOR 3282722.
  31. ^ Shotts, Emmett B.; Andrews, Charles L.; Sulzer, Catherine; Greene, Ellen (1971). "Leptospirosis in cottontail and swamp rabbits of the Mississippi River delta". Journal of Wildlife Diseases. 7 (2): 115–117. doi:10.7589/0090-3558-7.2.115. ISSN 0090-3558.
  32. ^ "Swamp rabbit". National Wildlife Federation. Retrieved February 11, 2025.
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