General
''Sylvilagus palustris hefneri'' was federally recognized as an endangered species on June 21, 1990. The urbanizedPhylogeny
The subspecies was first described in a publication in the '' Journal of Mammalogy'' in 1984 by James D. Lazell Jr, after his research was funded in part by a generous contribution from the Playboy Corporation.Lazell, J.D. JrSize
''Sylvilagus palustris hefneri'' is small-to-medium-sized, in length and in weight. Their hind feet range from and their ears range from in length. ''S. p. hefneri'' is the smallest of the three marsh rabbit subspecies, the others being ''Sylvilagus palustris paludicola'' and ''Sylvilagus palustris palustris''. These rabbits do not appear to be sexually dimorphic.Appearance
The pelage of ''S. p. hefneri'' is short with dark brown fur and a greyish-white belly, and their tails are dark brown. ''S. p. hefneri'' is the smaller than the mainland marsh rabbit (''S. p. palustris'') and Upper Keys marsh rabbits (''S. p. paludicola'') and is distinguished by its dark fur. ''S. p. hefneri'' also differs from ''S. p. palustris'' and ''S. p. paludicola'' in several cranial characteristics. The Lower Keys marsh rabbit has a shorter molariform tooth row, higher and more convex frontonasal profile, broader cranium, and elongated dentary symphysis.Range
''Sylvilagus palustris hefneri'' has been isolated to the Keys by the rise in sea level and human inhabitation to the local area.Reed, Robert N. "An Ecological Risk Assessment of Nonnative Boas and Pythons as Potentially Invasive Species in the United States." Risk Analysis: An International Journal 25.3 (2005): 753-766. This isolation may be the cause for the subspeciation from the Upper Keys marsh rabbit, ''Sylvilagus palustris paludicola''. Forys et al. determined the habitat occupied of ''S. p. hefneri'' to be in 1995 with 81 suitable habitats.Forys, E.A. 1995. Metapopulations of marsh rabbits: a population viability analysis of the Lower Keys marsh rabbit (Sylvilagus palustris hefneri). PhD. Thesis, University of Florida; Gainesville, Florida. In 1996, Forys refined the habitat to be about . An average home range of was determined in 1999. This range includes a few of the larger Lower Keys, specifically, Boca Chica, Saddlebunch, Sugarloaf, and Big Pine Keys and the small islands near these Keys. From 2001 to 2005, Faulhaber et al. surveyed the predetermined habitat to establish a current habitat range.Faulhaber, Craig A., et al. "Updated Distribution of the Lower Keys Marsh Rabbit." Journal of Wildlife Management 71.1 (2007): 208-212. They determined the median size of occupied patches was with an interquartile range of . This data is representative of 112 patches of occupied ''S. p. hefneri'' habitat (547.1 ha = total), with the note that the data represents an increased search area rather than an increased rabbit number. There was a net loss (—6) in patch occupancy between the 2001-2005 and 1988-1995 survey periods. Possible reasons attributing to this loss are stray cat predation, rise in sea level, and storm surges from hurricanes.Habitat
''Sylvilagus palustris hefneri'' is habitat specific choosing higher elevations within salt marsh or freshwater marsh but depend on herbaceous plants for food, cover and nesting. This vegetation includes species such as sawgrass (''Foraging
''Sylvilagus palustris hefneri'' is diet-specific, choosing particular vegetation; however foraging strategies are not affected by sex or seasonality. The major vegetative species found in the Keys include grasses (''Behavior
Faulhaber et al. conducted a study in 2006 to survey the diurnal habits seen in ''S. p. hefneri'' to ultimately provide conservationists with appropriate parameters for habitat extension.Faulhaber, Craig A., et al. "Diurnal Habitat Use by Lower Keys Marsh Rabbits." Journal of Wildlife Management 72.5 (2008): 1161-1167. They determined that when ''S. p. hefneri'' were in brackish wetlands they typically clustered together in patches of saltmarsh or buttonwoods. And when in freshwater wetlands they typically clustered together in patches of freshwater hardwoods.Reproduction
''Sylvilagus palustris hefneri'' produce fewer offspring, at an average of 3.7 litters per year, compared to other marsh rabbits at 5.7 litters per year. Sexual maturity in ''S. p. hefneri'' begins at about nine months of age. Researchers have found that the majority of males disperse at this time, yet females remain in their home range. ''S. p. hefneri'' are polygamous and do not display an apparent seasonal breeding pattern.Threats
''Sylvilagus palustris hefneri'' is considered an endangered species and is threatened by many different sources such as habitat alteration, contaminants, vehicular traffic, dumping, poaching, predation from introduced species (such as free-roaming domestic cats, dogs, feral hogs and fire ants), sea level rise and exotic vegetation. (14) More than half the area of suitable ''S. p. hefneri'' habitat has been destroyed for construction of residential housing, commercial facilities, utility lines, roads, or other infrastructure in the Lower Keys. Most of the remaining suitable habitat has been degraded by exotic invasive plants, repeated mowing, dumping of trash, and off-road vehicle use.Conservation
Many biologists and such have taken a close look at ''S. p. hefneri'' to determine and implement current conservation efforts. Action is currently underway at the species level and the habitat level. The most prominent method of conservation of ''S. p. hefneri'' is reintroducing the rabbits to unoccupied but potentially suitable patches Faulhaber et al. created a plan to restore or enhance key macro- and microhabitat more effectively by preventing harmful intrusion by humans, connecting isolated habitat patches, and mitigating barriers to rabbit movement. LaFever et al. demonstrate the use of population viability analysis as a conservation planning tool for reducing human wildlife conflicts.LaFever, David H., et al. "Use of a population viability analysis to evaluate human-induced impacts and mitigation for the endangered Lower Keys marsh rabbit." Human-Wildlife Conflicts 2.2 (2008) Crouse et al. conducted a genetic analysis comparing haplotypes in mitochondrial DNA to identify barriers in gene flow.Crouse, Amanda L., et al. "Population Structure of the Lower Keys Marsh Rabbit as Determined by Mitochondrial DNA Analysis." Journal of Wildlife Management 73.3 (2009): 362-367. Other possible methods into habitat conservation are: *Protection of important wildlife corridors **Several marsh rabbit populations are linked by corridors of low marsh and mangroves. Protection of these areas will aid in avoiding negative impact on the rabbit. *Removal of invasive exotic vegetation **Invasive species kill undergrowth, destroying the rabbit's food, shelter and nesting sites, their removal is necessary to restoring habitat *Fencing or barricading areas of off-road vehicle (ORV) use and/or dumping *Improving habitat by planting or encouraging native plant species *Monitor the status of ''S. p. hefneri'', examine ecological processes, and increase public awareness of ''S. p. hefneri'' habitat and instill stewardship. Species-level conservation action is as follows: *Investigate components of both occupied and unoccupied marsh rabbit habitat and determine why rabbits are present or absent *Maintain and improve the GIS database for ''S. p. hefneri'' information *Conduct ''S. p. hefneri'' reintroductions from natural wild populations *Utilize federal regulatory mechanisms for protection ** Federal activities may cause jeopardy for the total population *Control or eliminate free-roaming cat populations near rabbit habitat **Free-roaming cats are a major threat to rabbit survival, establishing a program throughout the Lower Keys to control free roaming cats can increase their survival and colonization of restored habitats *Minimize road mortality by implementing slower speed zones and increase enforcement of existing zones, and by controlling poaching.See also
* List of organisms named after famous people (born 1900–1949)References
{{Taxonbar, from=Q5491270 Sylvilagus Endangered fauna of the United States Endemic fauna of Florida Mammals described in 1984 Playboy ESA endangered species