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robust cottontail

Sylvilagus robustus

What do they look like?

Robus cottontails They are light gray rabbits with large ears, light gray backs, and darker fur farther down their back. They are brownish on their shoulders and top of their tail, and white underneath. Like other cottontail rabbits, they have big feet and ears and cutting edges on their teeth. They have very furry feet. They are most closely related to eastern cottontails, but they are bigger and their skulls have different shapes. (Chapman and Litvaitis, 2003; Ruedas, 1998; Schmidly and Davis, 1994)

  • Sexual Dimorphism
  • female larger
  • Range mass
    1.3 to 1.8 kg
    2.86 to 3.96 lb
  • Average length
    416 mm
    16.38 in

Where do they live?

Robust cottontails, which are also called Davis Mountain cottontails, live in mountains of the southern United States and northern Mexico. They live between the Rio Grande River in New Mexico and the East Pecos River in Texas. This area has a lot of mountains, including the Guadalupe, Davis, Chinati, and Chisos Mountain ranges. For a while, scientists thought they no longer lived in the Chisos Mountains, but they were found there again between 2007 and 2012. They are also found in the Coahuila Range in Mexico, which is farther south than researchers originally though they lived. (Vestal, 2005)

What kind of habitat do they need?

Robust cottontails live in mountain forests with pinyon pine trees, oak trees, and junipers. The places where they live are dry with brush and shrubs. They usually live in sumac or mahogany, and only come out in the evening to eat. Robust cottontails live at elevations of 4,700 to 8,000 feet. (Schmidly, 1977; Vestal, 2005)

  • Range elevation
    460 to 2440 m
    1509.19 to 8005.25 ft

How do they reproduce?

The mating behavior of robust cottontails is probably similar to its relatives. They breed at higher elevations than eastern cottontails. Cottontail rabits almost always have social systems where some males dominate others and get more chances to mate. They determine which males get to be dominant by being aggressive with each other. Their courtship includes body language, and mostly happens at night. Both males and females mate with more more than one other rabbit. (Chapman and Litvaitis, 2003)

Female cottontail rabbits can have up to 5 sets of offspring in the same year. Robust cottontails usually have around 4 young at a time, but this changes with the time of year, environmental conditions, available food, and how old the mother is. The first set of young a female every has usually has 2.95 to 5.10 rabbits. The newborns are born in a nest, and can't take care of themselves at first. They are usually able to breed after they are 1 year old. (Chapman and Litvaitis, 2003)

The development of robust cottontails is probably similar to eastern cottontails. Eastern cottontails develop in their mother for 25 to 35 days, and usually about 28. They weigh 35 to 45 g when they are born. They open their eyes between day 6 and 7. They start going outside the nest by day 12, and stop drinking milk by day 15. (Chapman and Litvaitis, 2003; Chapman, 1982; Schmidly and Davis, 1994)

  • How often does reproduction occur?
    Females breed up to 5 times per year.
  • Breeding season
    Because they breed at higher elevations, the breeding season of robust cottontails in most populations lasts all year.
  • Range number of offspring
    3.60 to 5.60
  • Average number of offspring
  • Range gestation period
    25 to 35 days
  • Average gestation period
    28 days
  • Average weaning age
    15 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Female robust cottontails are mostly responsible for caring for their young. Mothers build nests for their young, which are holes in the ground in a protected spot. They line line the holes with leaves and a layer of their own fur. The nests are about 12.5 cm long, 10.4 cm wide, and 9.1 cm deep. When the young are born, they are blind, naked, and completely dependent on their mothers. Mothers care for their young until they are able to leave the nest. (Bothma, et al., 1977; Chapman and Litvaitis, 2003)

  • Parental Investment
  • altricial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

How long do they live?

Robust cottontails can live up to 3 years in the wild, and up to 8 years in captivity. They are most likely to get eaten by predators. (Lee, 2000)

  • Range lifespan
    Status: wild
    3 (high) years
  • Range lifespan
    Status: captivity
    8 (high) years

How do they behave?

Robust cottontails recently became their own species and they are hard to find in the wild, so scientists don't know very much about their specific behavior. However, they probably are very similar to eastern cottontails. Eastern cottontails are solitary and congregate only during the mating season, when males often interact aggressively in competition for mates. Cottontail species are predominantly active between dusk and dawn, times at which it is safest to enter open areas and leave their protective brush environment. In areas where predator populations have been reduced by humans, densities can reach 20 rabbits per hectare. In other areas, densities can be as low as 1 individual per hectare. Territory size varies greatly by population and is dependent on available vegetation. (Chapman and Litvaitis, 2003; Schmidly and Davis, 1994)

Home Range

Cottontails don't usually have territories. The area where they live and travel overlaps between rabbits where there are enough shrubs and food in the late fall and winter. However, females don't overlap in the breeding season. The size of the area where they live depends a lot on the season and how good the habitat is for them. (Chapman and Litvaitis, 2003)

How do they communicate with each other?

Communication and perception in robust cottontails is very similar to other cottontails. They mostly choose mates based on scents, which come from under the chin and around the groin. Males compete for females and also use body language to show off to them. Cottontails don't usually make noise, but do make high-pitched squeals as a warning when they are attacked by a predator. They sometimes drum their back feet loudly as a warning. (MacDonald, 2001)

What do they eat?

Like other cottontails, robust cottontails can only eat plants. The kind of plants they eat depends a lot on what is available around where they live. They eat grasses and other flowering plants. In the wintertime, there aren't as many plants available, and they eat twigs and bark on shrubs and small trees. Many cottontails also eat their own fecal pellets, but scientists don't know if robust cottontails do this or not. (Chapman and Litvaitis, 2003)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • flowers
  • Other Foods
  • dung

What eats them and how do they avoid being eaten?

Robust cottontails are eaten by a few different kinds of mammals and birds, which probably include gray foxes, bobcats, golden eagles, and great horned owls. Cottontails hide from predators in shrubs, and stay away from open areas except at night. If a predator is nearby, they stay still and quiet and rely on their camouflage coloring. (MacDonald, 2001; Nowak, 1999; Schmidly and Davis, 1994)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Robust cottontails are important as food for their predators. Their populations go up and down and have a high point about every ten years. They also get parasites, especially ticks. These ticks carry the bacteria that causes Rocky Mountain spotted fever. They also get fleas from the families Pulicidae and Leptopsyllidae, and warbles. Parasites found inside their bodies are roundworms from the groups Obeliscoides, Trichostrongylus, Longistriata, and Trichuris. They also get two kinds of tapeworms, which are Mosgovoyia and Taenia. (Chapman and Litvaitis, 2003)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • ticks (Ixodidae)
  • fleas (Pulicidae)
  • fleas (Leptopsyllidae)
  • warbles (Cuterebridae)
  • nematodes (Obeliscoides)
  • nematodes (Trichostrongylus)
  • nematodes (Longistriata)
  • nematodes (Trichuris)
  • cestodes (Mosgovoyia)
  • cestodes (Taenia)

Do they cause problems?

Robust cottontails have occasionally damaged orchard trees, gardens, or crops. However, they don't really live near humans, like eastern cottontails do. (Chapman and Litvaitis, 2003)

  • Ways that these animals might be a problem for humans
  • crop pest

How do they interact with us?

Robust cottontails are sometimes hunted by humans. However, they may not be be the best species to hunt because they live in such a small area, so they might not survive very well if they are hunted a lot. (Chapman and Litvaitis, 2003)

  • Ways that people benefit from these animals:
  • food
  • body parts are source of valuable material

Are they endangered?

Robust cottontails are endangered according to the IUCN Red List. However, they were just recently listed as their own species, so scientists aren't sure if the number of them is increasing or decreasing. Many other groups haven't listed them as endangered yet. (Ruedas and Smith, 2011)

Some more information...

Robust cottontails have gone back and forth between being classified as their own species and being a subspecies of eastern cottontails.


Stephanie Schuyler (author), Yale University, Eric Sargis (editor), Yale University, Rachel Racicot (editor), Yale University, Tanya Dewey (editor), University of Michigan-Ann Arbor, Catherine Kent (editor), Special Projects.


Bothma, J., P. Du, J. Teer. 1977. Reproduction and productivity in South Texas cottontail rabbits. Mammalia, 41/3: 253-281.

Chapman, J. 1982. Latitude and Gestation Period in New World Rabbits. The American Naturalist, 124/3: 442-445.

Chapman, J., G. Ceballos. 1990. Rabbits, hares, and pikas: status survey and conservation action plan. Gland, Switzerland: IUCN.

Chapman, J., J. Litvaitis. 2003. Eastern Cottontail: Sylvilagus floridanus and allies: Wild Mammals of North America: Biology, Management, and Conservation. Baltimore, MD: Johns Hopkins University Press.

Lee, D., R. Pfau, L. Ammerman. 2010. Taxonomic status of the Davis Mountains cottontail, Sylvilagus robustus, revealed by amplified fragment length polymorphism. Journal of Mammalogy, 91/6: 1473-1483.

Lee, E. 2000. "Sylvilagus floridanus" (On-line). Penn State New Kensington Species Page. Accessed April 01, 2012 at

MacDonald, D. 2001. Sylvilagus. Pp. 457-460 in D MacDonald, ed. The Oxford Encyclopedia of Mammals, Vol. 1/1, 3rd Edition. London: Oxford University Press.

Nowak, R. 1999. Walker’s Mammals of the World, Sixth ed. Baltimore, MD: Johns Hopkins University Press.

Ruedas, L. 1998. Systematics of Sylvilagus Gray (Lagomorpha: Leporidae) from Southwestern North America. Journal of Mammalogy, 79/4: 1355-1378.

Ruedas, L., A. Smith. 2011. "Sylvilagus robustus" (On-line). IUCN Red List of Threatened Species. Accessed April 01, 2012 at

Schmidly, D., W. Davis. 1994. The Mammals of Texas. Austin, TX: Texas Park and Wildlife Department.

Schmidly, D. 1977. Mammals of the Trans-Pecos. College Station, TX: Texas A&M University Press.

Smith, A. 2008. Conservation of Endangered Lagomorphs. Heidelberg: Springer Verlag.

Vestal, A. 2005. Genetic Variation in the Davis Mountain Cottontail (Sylvilagus robustus). ProQuest Dissertations and Theses, 1/1: 1-71.

University of Michigan Museum of ZoologyNational Science Foundation

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Schuyler, S. 2012. "Sylvilagus robustus" (On-line), Animal Diversity Web. Accessed April 21, 2024 at

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