San Jose Shrub Rabbit

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San Jose Shrub Rabbit
Systematics
Subclass : Higher mammals (Eutheria)
Superordinate : Euarchontoglires
Order : Hare-like (Lagomorpha)
Family : Hares (Leporidae)
Genre : Cottontail Rabbit ( Sylvilagus )
Type : San Jose Shrub Rabbit
Scientific name
Sylvilagus mansuetus
EW Nelson , 1907

The San José shrub rabbit ( Sylvilagus mansuetus ) is a species of mammal from the genus of cottontail rabbits within the hare-like species . It is endemic to Isla San José in the Gulf of California .

features

The San José shrub rabbit reaches a body length of about 34 centimeters with a tail of about 4.4 centimeters in length. The hind foot is 7.3 inches long, the ear (dried) about 6.3 inches long. The weight is about 800 grams. Accordingly, it is a small species within the genus. The back color and the tail are pale sand-colored, gray-brown or dark brown, the sides of the body are a little lighter and grayer. The belly side and the underside of the tail are colored whitish. The ears are gray, the neck area darker gray to ocher in color. The front legs are also ocher in color and merge with the white feet. The rear area of ​​the hind feet is brown and darker than the back color, the front area is white. Compared to the closely related and on the neighboring peninsula Baja California occurring brush rabbit ( S. bachmani ) is the fur a little brighter and the ears are slightly longer. In winter fur, the top of the head and back is pale sand-colored to yellow-gray, the sides are paler and grayer than the back.

Skull of Sylvilagus mansuetus

The skull has a long and narrow snout region. The supraorbital processes are wide and compact.

The karyotype consists of a chromosome set of 2n = 48 chromosomes.Together with the shrub rabbit, it is the only species of cottontail rabbit that has the same set of chromosomes, which also occurs in the species of the genus Lepus and Romerolagus and is originally recognized as being within the rabbits.

distribution

Distribution area of ​​the San José shrub rabbit

The San José brush rabbit is endemic to the to the Mexican state of Baja California Sur belonging Isla San José in the Gulf of California . The island is about 170 km² and is 60 kilometers north of the city of La Paz ; from the mainland it is about five kilometers away.

An inventory in 2011 revealed that the species only inhabited an area of ​​around 20 km² on the island along the south-western coastal plain with a single population . It is the smallest known distribution area of ​​a species within the hare-like species.

Way of life

Very little information is available about the species' way of life. The animals are most active between sunset and around 2:00 a.m. and in the morning between 6:00 a.m. and 10:00 a.m.

The populated habitats are dry desert areas, the areas with the densest occurrences of the species are characterized by a high number and variety of desert trees, cacti and shrubbery. The plant of the area include Fouquieria digueti , Jatropha cinerea , Pachicerus pringley , Opuntia cholla , Bursera hindsiana , Bursera microphylla , Simmondsia chinensis , peninsular Cercidium , Stenocereus gummosus , Cyrtocarpa edulis , Esenbeckia flava , Lycium sp. and Olneya tesota . The rabbits use the shade under the plants as a resting place. They probably feed on various plant materials, although there have been no analyzes of the specific food composition so far.

Only very limited information is available about the reproduction of the animals. In November 2008 two pregnant females with two embryos and two lactating females and two nests each were documented. The nests were each in a burrow at the foot of desert plants or opuntia . One nest had an entrance with a diameter of 11 to 12 centimeters and had a brood chamber at a depth of 15 centimeters with a length of about 8 centimeters; it contained two dead young animals and was padded with fur and plant material. The second nest had an approximately narrower entrance of 8.5 × 10.5 centimeters and was 12 centimeters deep in the ground. This was also padded, there were no young animals in it.

In addition to the San José shrub rabbits, only six other native mammal species live on the island. Other mammals include the mule deer ( Odocoileus hemionus ), the San Jose kangaroo rat (Dipodomys insularis), the pocket mouse Chaetodipus spinatus , the American bush rat Neotoma lepida , the North American catfish ( Bassariscus astutus ) and the cactus mouse ( Peromyscus erem ).

The rabbits' predators are mainly introduced cats and dogs, which exert a predatory pressure on all small mammals on the island. As the only native predator, the North American cat fret is also likely to prey on individual animals, but has little overlap in its habitat. Other domestic carnivores are different queues as the rattlesnake Crotalus enyo enyo , C. mitchelli mitchelli and C. ruber lucanensis that Bull snakes Pituophis melanoleucus bimaris and P. vertebralis , the Osprey ( Pandion haliaetus ), the Red-tailed ( Buteo jamaicensis ), the Peregrine ( Falco peregrinus ) and the great spotted falcon ( Falco sparverius ).

Systematics

The San José shrub rabbit is assigned to the cottontail rabbit (genus Sylvilagus ) as an independent species . It was first scientifically described by Edward William Nelson in 1907 under the scientific name Sylvilagus manseatus , which is still valid today . The species name manseatus is derived from the Latin name of the word "tame" and is probably due to the animals' very short flight distance .

The shrub rabbit ( Sylvilagus bachmani ) is the closest related species of the San José shrub rabbit

It is believed that the San José shrub rabbit is closely related to the shrub rabbit ( S. bachmani ) that lives on the mainland of the Baja California peninsula . The exact family relationship is unknown, the San José shrub rabbit could also be a subspecies of the shrub rabbit, but is generally regarded as a separate species due to its isolation . Due to the small genetic differences, the San José shrub rabbit is sometimes also viewed as a subspecies of the shrub rabbit and studies from 2016 placed it as a sister group of S. bachmani cerrosensis from Isla de Cedros within S. bachmani .

Hazard and protection

The San José shrub rabbit is classified by the International Union for Conservation of Nature and Natural Resources (IUCN) as critically endangered due to the size of the population and the very small distribution area. The maximum estimated population is 500 to 700 animals, although the real population can also be significantly lower. Comparisons between censuses from 1995/96 and 2008 have shown that the population of the San José shrub rabbit has declined. The reasons for this could be hunting pressure from imported cats and dogs, loss of habitat due to competition with imported goats, illegal hunting or the effects of the establishment of a salt mine and a tourist area with a golf course, private airport and marina close to the rabbit's distribution area. All mammal species on the island are under Mexican conservation.

supporting documents

  1. ↑ a b c d e f g h i j San Jose Brush Rabbit. In: SC Schai-Braun, K. Hackländer: Family Leporidae (Hares and Rabbits) In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (editor): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, p. 115. ISBN 978-84-941892-3-4 .
  2. ↑ a b c d e f Howard H. Thomas, Troy L. Best : Sylvilagus mansuetus . In: Mammalian Species . tape 464 , 1994, pp. 1–2 ( full text (PDF; 219 kB)).
  3. ↑ a b c Joseph A. Chapman, John EC Flux (Ed.): Rabbits, Hares and Pikas. Status Survey and Conservation Action Plan. (PDF; 11.3 MB) International Union for Conservation of Nature and Natural Resources (IUCN), Gland 1990; P. 104. ISBN 2-8317-0019-1 .
  4. ↑ Consuelo Lorenzo, Sergio Ticul Álvarez-Castañeda, Jorge Vázquez: Conservation Status of the Threatened, Insular San Jose Brush Rabbit (Sylvilagus mansuetus). Western North American Naturalist 71 (1), 2011: pp. 10-16. ( Abstract )
  5. ↑ a b c d e f g Sylvilagus mansuetus in the endangered Red List species the IUCN 2011. Posted by: S. Álvarez Castañeda, C. Lorenzo, 2008. Accessed July 8 2012th
  6. ↑ Don E. Wilson & DeeAnn M. Reeder (eds.): Sylvilagus mansuetus in Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed).
  7. ↑ Sergio Ticul Álvarez-Castañeda, Consuelo Lorenzo: Genetic evidence supports Sylvilagus mansuetus (Lagomorpha: Leporidae) as a subspecies of S. bachmani. Zootaxa 4196 (2), 2016; Pp. 289-295. doi : 10.11646 / zootaxa.4196.2.7

literature

Web links

Commons : Sylvilagus mansuetus  - Collection of images, videos and audio files