Swamp rabbit (Sylvilagus aquaticus) demographics, morphometrics, and reproductive characteristics in Mississippi.ABSTRACT Wildlife agencies have been concerned about possible swamp rabbit (Sylvilagus aquaticus) declines, however swamp rabbits have tended to be one of the least studied members of Sylvilagus. During the 1997-98, 1998-99, and 1999-2000 harvest seasons, we characterized sex and age ratios, reproductive status, body mass, and hind hind 1. emanating from or pertaining to hindlimb. 2. adult female deer, especially red and other large species. blue hind a hind which has not borne young. foot length of harvested swamp rabbits on Trim Cane Wildlife Management Area, Mississippi, to better understand their demographics The attributes of people in a particular geographic area. Used for marketing purposes, population, ethnic origins, religion, spoken language, income and age range are examples of demographic data. and morphometrics Generally, morphometrics (from the Greek: "morph," meaning shape or form, and "metron”, meaning measurement) comprises methods of extracting measurements from shapes. In most cases applied to biological topics in the widest sense. . Swamp rabbit sex ratios did not differ among years ([[chi square chi square (kī), n a nonparametric statistic used with discrete data in the form of frequency count (nominal data) or percentages or proportions that can be reduced to frequencies. ].sub.2] = 0.01,[P.bar] = 0.907). Age ratios for swamp rabbits did differ marginally among years ([[chi square].sub.2] = 3.01, [P.bar] = 0.083). Swamp rabbits exhibited pregnancy in January (6%) with greater evidence of pregnancy (46%) in February. We did not detect a difference in body mass ([F.sub.1,111] = 0.74, [P.bar] = 0.391) or hindfoot length ([F.sub.1,111] = 0.89, [P.bar] = 0.349) between the sexes for swamp rabbits. Although we did detect a marginal difference in hindfoot length ([F.sub.1,111] = 3.38, [P.bar] = 0.069) between ages, we did detect a difference in body mass ([F.sub.1,144] = 107.51, [P.bar] <0.001). Swamp rabbit populations appeared to be sensitive to late season harvest, as measured by timing of conception, pregnancy, and changes in age ratio. States with swamp rabbits and rabbit harvest seasons that end in late winter should consider investigating effects of harvest season length on swamp rabbit population dynamics Population dynamics is the study of marginal and long-term changes in the numbers, individual weights and age composition of individuals in one or several populations, and biological and environmental processes influencing those changes. . INTRODUCTION Wildlife agencies have been concerned about possible swamp rabbit (Sylvilagus aquaticus) declines, however swamp rabbits have tended to be one of the least studied members of Sylvilagus (Martinson et al., 1961; Chapman and Feldhamer, 1981; Palmer et al., 1991; Dailey et al., 1993). Over the past several decades, swamp rabbit habitat has deteriorated leading to declines in many areas within their geographic range (Martinson et al., 1961; Terrel, 1972; Chapman and Feldhamer, 1981; Chapman et al., 1982; Palmer et al., 1991; Dailey et al., 1993). Swamp rabbits begin breeding in mid-February (Hill, 1967) until August, except for Texas (suggested year-round; Hunt, 1959) and Louisiana (observed pregnancies in all months except October; Svihla, 1929). Juvenile swamp rabbits are capable of breeding the year of their birth, but there are few reports of juveniles actually breeding (Chapman and Feldhamer, 1981). Therefore, there is potential of harvesting swamp rabbits during their breeding season Breeding season is the most suitable season usually with favorable conditions and abundant food and water when wild animals and birds (wildlife) have naturally evolved to breed to achieve the best reproductive success. . Considering the ecological importance of swamp rabbits and their status as a game animal in Mississippi, along with the general belief in their decline, it is of upmost importance to understand their population dynamics. Terrel (1972) commented that wildlife agencies were not able to collect pertinent data from trapping trapping, most broadly, the use of mechanical or deceptive devices to capture, kill, or injure animals. It may be applied to the practice of using birdlime to capture birds, lobster pots to trap lobsters, and seines to catch fish. because of cost and labor consumed related to amount of data collected. Data with the least bias is from hunter bag checks (Chapman et al., 1982). Petrides (1951) reported the importance of sex and age ratios in providing valuable indications of population characteristics. Therefore, we collected swamp rabbit age and sex ratio, reproductive status, body mass, and hind foot lengths from mandatory hunter bag checks and examined them among years to better understand population demographics and morphometrics. METHODS AND MATERIALS Trim Cane Wildlife Management Area (TCWMA) is located approximately 10 kilometers north of Starkville in Oktibbeha County, Mississippi Oktibbeha County is a county located in the U.S. state of Mississippi. As of 2000, the population was 42,902. Its county seat is Starkville6. Oktibbeha is a Native American word meaning either bloody water (because of a battle fought on the banks) or possibly icy creek. . Trim Cane Wildlife Management Area consists of 320 hectares that was converted from hardwood hardwood: see wood. hardwood Timber obtained from broad-leaved, flower-bearing trees. Hardwood trees are deciduous trees, except in the warmest regions. bottomland forest to agricultural fields during the early 1970s and was farmed until 1986 (Taylor, 1996); then, the area succeeded naturally into oldfield and hedgerow hedgerow Fence or boundary formed by a dense row of shrubs or low trees. Hedgerows enclose or separate fields, protect the soil from wind erosion, and serve to keep cattle and other livestock enclosed. habitats. We examined swamp rabbit population demographics and morphometrics on TCWMA during the 1997-98, 1998-99, and 1999-2000 harvest seasons. Prior to the 1997-98 harvest season, swamp rabbits were not harvested for >8 years. There were 3, 2-day weekend hunts in November and 2, 2-day weekend hunts in October, December, January, and February during each season. Two hunting parties were drawn for each weekend hunt. Each party consisting of [less than or equal to]3 hunters was limited to a harvest of 6 swamp rabbits/day because of TCWMA's small size. During most hunts a biologist, technician, or graduate student observed the hunt to process rabbits and determine hours hunted. We recorded sex, body mass (g), and hind foot length (mm) for each harvested rabbit. Additionally, we noted if a male's testes testes or testicles Male reproductive organs (see reproductive system). Humans have two oval-shaped testes 1.5–2 in. (4–5 cm) long that produce sperm and androgens (mainly testosterone), contained in a sac (scrotum) behind the penis. were regressed or descended, and if females were anestrous an·es·trous adj. 1. Not exhibiting estrus. 2. Of or relating to anestrus. or pregnant. We collected reproductive tracts from females and placed them in 10% formalin formalin /for·ma·lin/ (for´mah-lin) formaldehyde solution. for·ma·lin n. An aqueous solution of formaldehyde that is 37 percent by weight. to determine fetus fetus, term used to describe the unborn offspring in the uterus of vertebrate animals after the embryonic stage (see embryo). In humans, the fetal stage begins seven to eight weeks after fertilization of the egg, when the embryo assumes the basic shape of the newborn counts. We collected eye lenses from all rabbits to determine age. We soaked eyes in 10% formalin for two weeks, then extracted lenses and oven dried them at 80[degrees]C for 7 days, and weighed them to the nearest 0.0001 grams (Martinson et al., 1961). We used Hill's (1967) eye lens weights to distinguish adult and juvenile swamp rabbits. We predicted age based on morphometrics using logistic regression In statistics, logistic regression is a regression model for binomially distributed response/dependent variables. It is useful for modeling the probability of an event occurring as a function of other factors. models developed by Bond et al. (2000) for swamp rabbits with damaged eyes due to harvest ([n.bar] = 24, 20%). Bond et al. (2000) were able to accurately (81%) predict age of swamp rabbits using body mass and hind foot length together in logistic regression equations. We investigated changes in population structure by comparing age and sex ratios among years. Since rabbits were not harvested for >8 years prior to implementation of experimental harvest, we assumed temporal changes in population age and sex ratios were attributed to harvest effects. We tested for population structure differences among years using a Mantel-Haenszel chi-square. We tested for body mass and hindfoot length differences between ages and sexes using a two-way analysis of variance, blocked by year. All analyses were performed in SAS (1) (SAS Institute Inc., Cary, NC, www.sas.com) A software company that specializes in data warehousing and decision support software based on the SAS System. Founded in 1976, SAS is one of the world's largest privately held software companies. See SAS System. [R] with an alpha level of 0.10. RESULTS AND DISCUSSION Hunters harvested 123 rabbits during 244 hours of hunting. Rabbit harvest rate (harvest/hr) typically increased from October to February. Over 3 years, swamp rabbit harvest rate ranged from 0.31-0.92. Most rabbits were harvested in December ([n.bar] = 37), January ([n.bar] = 32) and February ([n.bar] = 36), whereas fewer rabbits were harvested in October ([n.bar] = 3) and November ([n.bar] = 15). The harvest trend we observed most likely was from the fact that earlier in the season it is warmer and scenting conditions are worse for dogs to trail rabbits, while late in the season as temperatures drop scenting conditions become better for dogs to locate and trail rabbits. Also, earlier in the harvest season there is more vegetation for concealment which makes harvesting harder, while late in the harvest season escape cover and vegetation is less dense all making harvest of rabbits easier. Swamp rabbit sex ratios did not differ among years ([[chi square].sub.2] = 0.01, [P.bar] = 0.907; 1997-98 = 42% females, 1998-99 = 52%, and 1999-2000 = 44%). Previous research on swamp rabbits documented 44% (Mississippi; Palmer et al., 1991) to 57% female (Texas; Hunt, 1959) swamp rabbits in the harvest, which was similar to our results. Swamp rabbit age ratios varied by year ([[chi square].sub.2] = 3.01, [P.bar] = 0.083; 1997-98 = 56% juveniles, 1998-99 = 75%, and 1999-2000 = 32%). Ranges of 32% (Texas; Hunt, 1959) to 61% (Missouri; Martinson et al., 1961) juvenile swamp rabbits in the harvest were previously reported, therefore our yearly estimates were similar to or greater than previously reported range. Swamp rabbits exhibited little evidence of breeding activity prior to February (pregnant: October-December = 0% and January = 6%; testes descended: October = 0%, November = 11%, December = 28%, and January = 13%) with greater reproductive activity during February (pregnant = 46% and testes descended = 50%). Previously in Mississippi, Palmer et al. (1991) reported that 38% of swamp rabbits were pregnant in February but made no report of January breeding activity. Although swamp rabbits have been documented to breed year-round in Texas (Hunt, 1959), we did not observe any swamp rabbits pregnant in October-December. Currently, to our knowledge no one has researched the latitudinal effects on swamp rabbit breeding. However, the differences observed between our part of Mississippi and Hunt's (1959) part of Texas could be from differences in latitude that has previously been observed in cottontail rabbits cottontail rabbit, animal of the order Lagomorpha, which includes the hares and rabbits, except for the domestic, or European, rabbit, which is in a separate species. (Sylvilagus floridanus Noun 1. Sylvilagus floridanus - widely distributed in United States except northwest and far west regions eastern cottontail cottontail, cottontail rabbit, wood rabbit - common small rabbit of North America having greyish or brownish fur and a tail with a ) by Barkalow (1962). The observed mean litter size of 1.8 ([n.bar] = 10, SE = 0.25, range 1-3) for pregnant swamp rabbits was the least reported compared to the previously reported range of 2.0 (Mississippi; Palmer et al., 1991) to 3.7 (Louisiana; Svihla, 1929). We did not detect a difference in body mass (male: 1935 grams, SE = 42.8; female: 1828 grams, SE = 40.7; [F.sub.1,111] = 0.74, [P.bar] = 0.391) between sexes swamp rabbits. Mean body masses observed for adult male (2214 grams) and female ([bar.x] = 2117 grams) swamp rabbits were comparable to others in Mississippi (males [bar.x] = 2236 grams, females [bar.x] = 2229 grams; Palmer et al., 1991), Indiana (males [bar.x] = 2254 grams, females [bar.x] = 2217 grams; Terrel, 1972), and Missouri (males [bar.x] = 2235 grams, females [bar.x] = 2161 grams; Holten and Toll, 1960), but were larger than those observed in Louisiana (males [bar.x] = 2013 grams, females [bar.x] = 2076 grams; Mullin, 1982; all adults combined 1698 grams; Lowery low·er·y also lour·y adj. Overcast; threatening. , 1974), and Alabama (males = 2059 grams, females = 2035 grams; Hill, 1967; Table 1). We detected a difference in body mass between ages (adult: 2179 grams, SE = 19.9; juvenile: 1689 grams, SE = 30.9; [F.sub.1,144] = 107.51, [P.bar] <0.001). Our mean body mass observed for juvenile male (1682 grams) and female (1695 grams) swamp rabbits were smaller than those observed previously in Mississippi (males [bar.x] = 2051 grams, females [bar.x] = 1981 grams; Palmer et al., 1991) and Missouri (males [bar.x] = 2022 grams, females [bar.x] = 1954 grams; Holten and Toll, 1960), but comparable to juveniles in Indiana (1776 grams; Terrel, 1972; Table 1). We did not detect a difference in hindfoot length (male: 104 millimeters, SE = 0.7; female: 102 millimeters, SE = 0.7; [F.sub.1,111] = 0.89, [P.bar] = 0.349) between sexes swamp rabbits. We detected a marginal difference in hindfoot length (adult: 104 millimeters, SE = 0.6; juvenile: 102 millimeters, SE = 0.7; [F.sub.1,111] = 3.38, [P.bar] = 0.069) between ages. We observed mean hind foot lengths of 105 millimeters (adult males), 103 millimeters (adult females), 103 millimeters (juvenile males), and 102 millimeters (juvenile females) for swamp rabbits, which were slightly larger than the overall mean of 101 millimeters (90-113 millimeters) reported by Lowery (1974) in Louisiana and slightly smaller than reported by Nelson (1909) 106 millimeters (Table 1). CONCLUSIONS In conclusion, most states (85%) with swamp rabbit harvest occurs during a portion of their breeding season, particularly February. We observed approximately 50% of all swamp rabbits reproductively active during February. We also observed that after the first year of harvest, proportion of juvenile swamp rabbits increased then correspondingly decreased after the second year of harvest below the initial harvest regime levels. We postulate postulate: see axiom. that continued hunting pressure during the late-season through 2 years led to the decrease in the proportion of juveniles during 1999-2000 below that of the 1997-98 level. Martinson et al. (1961) and Palmer et al. (1991) suggested that swamp rabbit populations may be susceptible to over-harvest. Considering our reduced bag limit, our results are conservative. We recommend states with swamp rabbits more aggressively investigate effects of harvest on population dynamics because of the decline in swamp rabbit habitat, the considerable amount of harvest during February among states, and the lack of published data on harvest effects on swamp rabbit population status. ACKNOWLEDGMENTS We thank all of the hunters, graduate students, S. Baker, P. Reynolds, D. Holt and Mississippi Department of Wildlife, Fisheries fisheries. From earliest times and in practically all countries, fisheries have been of industrial and commercial importance. In the large N Atlantic fishing grounds off Newfoundland and Labrador, for example, European and North American fishing fleets have long and Parks conservation officers for their cooperation during this study. Mississippi Department of Wildlife, Fisheries and Parks funded this project with a special small game research contract. This study was conducted under the authorization of Mississippi State University Mississippi State University, at Mississippi State, near Starkville; land-grant and state supported; coeducational; chartered 1878 as an agricultural and mechanical college, opened 1880. From 1932 to 1958 it was known as Mississippi State College. Institute of Animal Care and Use Committee Protocol Number 97-022. We thank the Delaware Agricultural Experiment Station The examples and perspective in this article or section may not represent a worldwide view of the subject. Please [ improve this article] or discuss the issue on the talk page. , Department of Entomology entomology, study of insects, an arthropod class that comprises about 900,000 known species, representing about three fourths of all the classified animal species. and Wildlife Ecology in the College of Agricultural and Natural Resources at the University of Delaware [3] The student body at the University of Delaware is largely an undergraduate population. Delaware students have a great deal of access to work and internship opportunities. for support during the analysis and writing phase of publication. LITERATURE CITED Barkalow, F. S., Jr. 1962. Latitude related to reproduction in the cottontail rabbit. J. Wildl Manage. 26:32-37. Bond, B.T., J.L. Bowman, B.D. Leopold, L.W. Burger, Jr., and K.D. Godwin. 2000. Delineating age and species of harvested cottontail cottontail a wild rabbit, Sylvilagus spp. and swamp rabbits. Proc. Annu. Conf. Southeast. Assoc. Fish and Wildl. Agencies. 54:330-336. Bothma, J. du P., and J. G. Teer. 1977. Reproduction and productivity in South Texas cottontail rabbits. Mammalia 41:253-281. Chapman, J.A., and G.A. Feldhamer. 1981. Sylvilagus aquaticus. Mammal mammal, an animal of the highest class of vertebrates, the Mammalia. The female has mammary glands, which secrete milk for the nourishment of the young after birth. . Sp. 151:1-4. Chapman, J.A., G.A. Feldhamer, and W.R. Edwards. 1982. Cottontails. p. 83-123 in J.A. Chapman and G.A. Feldhamer editor. Wild Mammal of North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. : Biology, Management, and Economics. John Hopkins University Press. Baltimore. Dailey, T.V., T.M. Vanglider, AND L.W. Burger, Jr. 1993. Swamp rabbit distribution in Missouri. Proc. Annu. Conf. Southeast. Assoc. Fish and Wildl. Agencies. 47:251-256. Hill, E.P. 1967. Notes on the life history of the swamp rabbit in Alabama. Proc. Annu. Conf. Southeast. Assoc. Game and Fish Comm See comms. . 21:117-123. Holten, J.W., and J.E. Toll. 1960. Winter weights of juvenile and adult swamp rabbits in southeastern Missouri. J. Wildl. Manage. 24:229-230. Hunt, T.P. 1959. Breeding habits of the swamp rabbit with notes on its life history. J. Mammal. 22:227-250. Lowery, G.H., Jr. 1974. The mammals The class Mammalia (the Mammals) is divided into two subclasses based on reproductive techniques: egg laying mammals (the Monotremes); and mammals which give live birth. The latter subclass is divided into two infraclasses: pouched mammals (the marsupials); and the placental mammals. of Louisiana CODE, OF LOUISIANA. In 1822, Peter Derbigny, Edward Livingston, and Moreau Lislet, were selected by the legislature to revise and amend the civil code, and to add to it such laws still in force as were not included therein. and its adjacent waters. Louisiana State University Press This article needs sources or references that appear in reliable, third-party publications. Alone, primary sources and sources affiliated with the subject of this article are not sufficient for an accurate encyclopedia article. , Baton Rouge Baton Rouge (băt`ən r  zh) [Fr.,=red stick], city (1990 pop. 219,531), state capital and seat of East Baton Rouge parish, SE La. .
Martinson, R.K., J.W. Holten, and G.K. Brachage. 1961. Age criteria and population dynamics of the swamp rabbit in Missouri. J. Wildl. Manage. 25:271-281. Mullin, K.D. 1982. Effects of selected silvacultural practices on swamp rabbit (Sylvilagus aquaticus) in disturbed bottomland hardwoods and associated pinewoods in west-central Louisiana. M.S. Thesis, Louisiana State University Louisiana State University and Agricultural and Mechanical College, generally known as Louisiana State University or LSU, is a public, coeducational university located in Baton Rouge, Louisiana and the main campus of the Louisiana State University System. , Baton Rouge. Nelson, E.W. 1909. The rabbits of North America. North Am. Fauna fauna All the species of animals found in a particular region, period, or special environment. Five faunal realms, based on terrestrial animal species, are generally recognized: Holarctic, including Nearactic (North America) and Paleartic (Eurasia and northern Africa); . 29:1-314. Palmer, W.E., G.A. Hurst, B.D. Leopold, and D.C. Cotton. 1991. Body weights and sex and age ratios for the swamp rabbit in Mississippi. J. Mammal. 72:620-622. Petrides, G.A. 1951. The determination of sex and age ratios in the cottontail rabbit. Am. Midl. Nat. 46:312-336. Svihla, R.D. 1929. Habits of Sylvilagus aquaticus littoralis. J. Mammal. 10:315-319. Taylor, J.D. II. 1996. Northern bobwhite bobwhite, common name for an American henlike bird of the family Phasianidae, which also includes the pheasant and the partridge. The eastern bobwhite quail (Colinus virginianus) is about 10 in. (25 cm) long. habitat use and reproductive success Reproductive success is defined as the passing of genes onto the next generation in a way that they too can pass those genes on. In practice, this is often a tally of the number of offspring produced by an individual. in managed oldfield habitats in Mississippi. M.S. Thesis. Mississippi State University, Mississippi State. Terrel, T.L. 1972. The swamp rabbit (Sylvilagus aquaticus) in Indiana. Am. Midl. Nat. 57:283-295. Bobby T. Bond (1), Jacob L. Bowman (2), Bruce D. Leopold (3), L. Wes Burger, Jr (3), K. David The Reverend Dr. K. David[1][2] was a Pastor, a New Testament Scholar, a Bible Translator and an able Administrator. He was a member in the Society for Biblical Studies in India (SBSI) Godwin (3), and Corey M. Class (3) (1) Georgia Department of Natural Resources The Georgia Department of Natural Resources is an administrative agency of the U.S. state of Georgia. The agency is charged with the responsibility of regulating hunting, fishing, boating, and non-game plants and animals. The agency is headed by a commissioner. , Wildlife Resources Division. 1014 Martin Luther King Blvd., Fort Valley, GA 31030. (2) Delaware Agricultural Experiment Station, Department of Entomology and Wildlife Ecology, College of Agricultural and Natural Resources, University of Delaware, Newark, DE 19717-1303, and (3) Department of Wildlife and Fisheries, Box 9690, Mississippi State University, Mississippi State, MS 39762. Bobby Bond corresponding author: Bobby Bond@dnr.state.ga.us.
Table 1. Body mass (BM--grams) and hind foot length (HFL--millimeters)
measurements and associated sample sizes (n) from swamp rabbits
(Sylvilagus aquaticus).
# = Genders combined
Adult Juvenile Juvenile
Location Measurement Female Adult Male Female Male
Mississippi BM 2117 2214 (n=30) 1695 1682
(our study) (n=17) (n=37) (n=33)
Mississippi BM 2229 2236 (n=19) 1981 2051
(Palmer et (n=11) (n=16) (n=20)
al. 1991)
Alabama (Hill BM 2035 2059 (n=144)
1967) (n=180)
Louisiana BM 2076 2013 (n=15)
(Mullin 1982) (n=17)
Louisiana BM 1698*
(Lowery 1974) (n=7)
Missouri BM 2161 2235 (n=44) 1954 2022
(Holton and (n=35) (n=49) (n=63)
Toll 1960)
Indiana BM 2217 2254 (n=7) 1776*
(Terrel 1972) (n=6) (n=7)
Mississippi HFL 103 105 (n=30) 102 103
(our study) (n=17) (n=37) (n=33)
Louisiana HFL 101*
(Lowery 1974) (n=7)
Geographic HFL 106*
range-wide (n=10)
(Nelson 1909)
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