There are 13 species of cottontail rabbits (genus Sylvilagus), nine of which are found in various sections of North America north of Mexico. All nine are similar in general appearance and behavior but differ in size, range, and habitat. Such differences result in a wide variation of damage problems, or lack of problems. The pygmy rabbit (S. idahoensis), found in the Pacific Northwest, weighs only 1 pound (0.4 kg), while the swamp rabbit (S. aquaticus), found in the southeastern states as far north as southern Illinois, may weigh up to 5 pounds (2.3 kg). Most species prefer open, brushy, or cultivated areas, but some frequent marshes, swamps, or deserts. The swamp rabbit and the marsh rabbit (S. palustris) are strong swimmers. The eastern cottontail (S. floridanus) is the most abundant and widespread species. For the purposes of the discussion here about damage control and biology, the eastern cottontail will be considered representative of the genus. Cottontail rabbits must be distinguished from jackrabbits and other hares, which are generally larger in size and have longer ears.

The eastern cottontail rabbit is approximately 15 to 19 inches (37 to 48 cm) in length and weighs 2 to 4 pounds (0.9 to 1.8 kg). Males and females are basically the same size and color. Cottontails appear gray or brownish gray in the field. Closer examination reveals a grizzled blend of white, gray, brown, and black guard hairs over a soft grayish or brownish underfur, with a characteristic rusty brown spot on the nape of the neck. Rabbits molt twice each year but remain the same general color. They have large ears, though smaller than those of jackrabbits, and the hind feet are much larger than the forefeet. The tail is short and white on the undersurface, and its similarity to a cotton ball resulted in the rabbit’s common name.

Resources: (online)
Cottontails