Sylvilagus graysoni
Tres Marias cottontail

Sylvilagus graysoni is restricted to the Tres Marias Islands, 100 km west of the coast of Mexico.(Nowak, 1999)

The habitat of Sylvilagus graysoni consists of dense vegetation, including trees and bushes. This species thrives in areas that provide cover, and does not prefer to be in open fields.

These rabbits seek shelter in burrows made by other animals, under piles of brush, or within the vegetation. (Schneider, 1990)

The Tres Marias cottontail is a medium to large-sized rabbit, with gray, brown, and red fur. Its underside is generally pale brownish-red, and the species is characterized by a brown patch of fur on its throat. Its tail is brown above and white below. These rabbits do not turn white during the winter.

The average head and body length ranges from 215-471 millimeters, while tail length varies from 15-60 millimeters. Compared to other species of cottontails, Sylvilagus graysoni has relatively short ears that are approximately 57 millimeters long. The average length of the rabbit's hind foot is 95 millimeters.

Females in the species have four or five pairs of mammae. There are no significant sexual dimorphism except that adult females tend to be slightly larger than adult males. (Cervantes, 1997; Schneider, 1990)

There is very little information on the reproduction of this species. The gestation period, number of young per birth, and number of litters per lifetime are unknown.

There is no mention of when in the year births are most likely to occur, the degree of development of the neonate, or the weight and length of the newborn rabbit.

There is no information regarding the estrous cycle of females, or of the mating systems of Tres Marias cottontails. (Cervantes, 1997; Nowak, 1999; Schneider, 1990)

Tres Marias cottontails are generally nocturnal, but are often seen during the daytime also. They are almost exclusively terrestrial, and are active throughout the year. This species of cottontails moves around using a characteristic "bunny hop."

It is not known whether these rabbits are a social or a solitary species. However, it is known that during breeding season, several males pursue estrous females together.

Females excavate a special protective shelter for the sake of rearing their young. The mother digs a hole approximately 150 millimeters deep and 120 millimeters wide. She then lines it with soft plants and fur from her underside. This nest is to ensure that the baby rabbits stay warm and safe. The female sits above the hole (not in it), and the newborns climb to the top to feed on her milk.

Tres Marias cottontails are able to protect themselves through their ability to remain almost completely still and silent for up to 15 minutes. This adaptive trait enables them to be undetected even when closely approached.

(Nowak, 1999; Schneider, 1990)

Tres Marias cottontails feed on a wide variety of plant material and herbaceous species. Their diet consists of bark and twigs during the colder months of the year.

This species, like other rabbits, excrete two kinds of fecal matter. The soft, green pellets are reingested in order to absorb vitamin B that can only be extracted after food is digested once. (Nowak, 1999; Schneider, 1990)

Tres Marias cottontails are hunted by humans. They benefit humans by providing game for hunters and valuable furs. (Cervantes, 1997; Nowak, 1999)

There is no evidence of Tres Marias cottontails adversely affecting humans. There is documentation of other species of cottontail rabbits damaging crops, forest plantations, and shrubs.

(Nowak 1999; Schneider, 1990)

Sylvilagus graysoni flourished throughout the Tres Marias Islands at the beginning of the century, but in the last survey of this species (1976) it was shown that its population has significantly dropped. In the last 10 years, the number of Sylvilagus graysoni has been reduced by 50 percent. This trend is anticipated to continue.

This species has evolved in an environment that is relatively predator-free, and therefore it is not prone to run away if approached by humans. Hunters kill these rabbits with minimal difficulty. Other threats to its survival include modification of its habitat by clearing of vegetation, newly introduced species such as pigs and goats, and human settlements.

Surveys have been recommended to determine the present status of the species. Research is being initiated with hopes of preserving the remainder of the species. (Cervantes, 1997; Hoffman, 1993)