|In the Appalachians of Virginia|
|Appalachian cottontail range|
The Appalachian cottontail (Sylvilagus obscurus) is a species of cottontail rabbit in the family Leporidae. It is a rare species found in the upland areas of the eastern United States. The species was only recognized as separate from the New England cottontail (Sylvilagus transitionalis) in 1992. 
The Appalachian cottontail, Sylvilagus obscurus, is a small rabbit inhabiting mostly mountainous regions in the eastern U.S. ranging from Pennsylvania to South Carolina and being most prominent in the Appalachians.  S. obscurus is better adapted to colder climates than its distant relative, S. floridanus, the eastern cottontail. S. obscurus is light-yellow brown, mixed with black on the dorsal side, having a brown and red patch mixed on the neck. The ventral side is mostly white.  The Appalachian cottontail and S. transitionalis, the New England cottontail, are not easily distinguished in the field, and are most easily identified geographically. Cottontails found south or west of the Hudson River are considered Appalachian cottontails, those found north and east are considered New England cottontails. The species can otherwise be identified by chromosome number and skull measurements.  Female Appalachian cottontails are typically larger than males with reproductive needs being the most likely cause. The weight of the Appalachian Cottontail can range from as little as 756 grams (1.667 lb) up to as much as 1,153 grams (2.542 lb). The average length is 408 mm (16.1 in). The lifespan of S. obscurus is rather short, less than a year in some cases. 
Sylvilagus obscurus is typically active around dusk or at dawn. During the day they typically avoid predators by sheltering under logs or in burrows. Hibernation does not play a factor, the rabbit being active year-round.  It is believed that there is a social hierarchy within the species especially when it comes to mating, in which the males assert their dominance by fighting to gain mating priority. 
Little is known about the reproductive habits of the Appalachian cottontail, but much can be based on knowledge of the genus Sylvilagus and the reproductive habits of most rabbits. Typically, they are inactive during midwinter, but as the nights shorten and the days lengthen, sexual activity develops strongly amongst Sylvilagus; the reason for this being that day length directly correlates with stimulation of FSH in the female’s blood which then in turn stimulates the follicles to develop ova.  This puts the female in " heat" until reproduction occurs, however there is no particular seasonal cycle as the female can remain in this state, deemed pre-estrus, for a while. The breeding season for the Appalachian cottontail has been found to be between February and October. Once fertilization occurs, the gestation period is about 28 days. Before giving birth, the female will begin to dig a nesting depression.  She then pulls out her fur from her underbelly and gathers berries and leaves in order to provide a lining for the nest. This hair-pulling also allows for the nipples to be exposed for the offspring to nurse. The offspring, when birthed, will live in the nest with vegetation until they are independent for about 3–4 weeks. Typically, a mother of the genus Sylvilagus will care for her young and visit the nest twice a day to nurse her offspring. An adult female can also breed up to 3-4 times per season and have roughly 3-4 offspring per litter. 
Appalachian cottontails are found in mountainous areas, typically from 610 to 762 m (2,001 to 2,500 ft) of elevation.  The Appalachian Mountains provide for S. obscurus a habitat with cover and vegetation such as blackberry, greenbriar, and mountain laurel.  Often this is what the Appalachian cottontail feeds on as well as bark and twigs of trees such as red maple, aspen, and black cherry. Usually its diet will consist of twigs, leaves, and fruits. Coprophagy, the eating of its own feces, often occurs as it is useful for it to take up certain vitamins and nutrients that weren’t digested well in the first pass of digestion. This type of diet is found in most of the genus Sylvilagus.
The Appalachian cottontail is adapted its role of prey, and because of this it typically has heightened senses of smell, hearing, and sight. This allows for the rabbit to notice predators and react quickly to threats.  Mothers have been observed performing a grunting sound in order to alert offspring to the presence of predators. Its senses are also used to find potential mates, and it has been discovered squealing at times when mating occurs. 
There are several threats that have endangered the survival of S. obscurus. These threats involve the destruction and maturation of habitat, as well as habitat fragmentation which is due to urban development. Once fragmentation has occurred the lack of cover exposes the cottontail to predators, increasing the strain on the species. Hunting is a common reason for deaths of many Appalachian cottontails but is mostly due to lack of knowledge by the hunter. The lack of knowledge of this species, because it is so secretive and rarely found in the wild, also contributes to its being threatened. 
Sylvilagus obscurus is a part of the family Leporidae. This family consists of 12 genera, containing a total of 62 species of lagomorphs. Lagomorphs are characterized by 2 pairs of incisors. Sylvilagus species are herbivores but have been seen to practice coprophagy. As with other lagomorphs, the tail is highly reduced, the jaw is perforated, and the soles of the feet are densely furred.  The generic name Sylvilagus is derived from Latin sylva (woods) and lagus (hare), together meaning "hare of the woods".  This genus consists of 13 different species which are found throughout North America, Central America, and northern South America.  Within the genus Sylvilagus there are many distant relatives of Sylvilagus obscurus such as Sylvilagus robustus which is found in the Guadalupe Mountains in Mexico at elevations as high as 1,400 m (4,600 ft) in woodland habitats similar to those of S. obscurus. 
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