68.
Santa Catarina’s Guinea Pig
(Cavia intermedia)
CR
Overview

Santa Catarina’s guinea pig is one of the rarest species on the planet because of its very small population size (approximately 42 individuals). It also has one of the smallest geographic distributions of any mammal – less than 10 ha. Its ancestors diverged from the mainland guinea pigs following the isolation of Moleques do Sul Island as a result of rising sea levels some 8,000 years ago.  Over this time period the species has evolved a number of characteristics that distinguish it from other guinea pigs: individuals show several adaptations to island life, such as high population density, stable age structure and small home range size. With such a small population size and range the species is particularly vulnerable to threats such as hunting and natural disasters.

Urgent Conservation Actions
Access rules for the protected area where this species occurs need to be enforced.
Distribution
Endemic to the 10-ha Moleques do Sul Island, southern Brazil.
Associated Blog Posts
26th Sep 11
This is one of the rarest species on the planet because of its very small population size (between 24 to 60 individuals). Santa Catarina's guinea pig (Cavia ...  Read

Media from ARKive
ARKive image - Santa Catarina's guinea pig
Evolutionary Distinctiveness
Order: Rodentia
Family: Caviidae

Santa Catarina’s guinea pig is regarded as phylogenetically closest to the mainland greater guinea pig, C. magna, from which it supposedly derived after Moleques do Sul Island was isolated by rising sea levels about 8,000 years ago. The two species share many similar morphologic, morphometric, and genetic traits, and are estimated to have diverged from other mammal species in the late Miocene.

Description
Size: 
Head and body length: 200 – 400 mm
Weight: Males : 577 – 721 g, Females: 602 – 740 g
Cavies have long, coarse fur with a crest of hairs at the neck. They are greyish or brownish in colour. Their build is stocky, with short limbs and short, unfurred ears. There is no external tail. They have four digits on the forefeet and three on the hind feet, all armed with sharp claws.
Ecology

The reproduction and growth rates of C. intermedia are reduced, even by caviomorph standards. Reproductive rates are low (78% of pregnant females with a single offspring), young are born quite large (19% of adult females’ weight), and sexual maturity is reached quite late (at around 59 days). The home-range size for C. intermedia (0.17 ha) is small in relation to home-range size for C. magna. These characteristics are consistent with the island syndrome whereby insular rodent populations display a suite of characteristics distinct from continental populations, regarding density (high and stable), age structure (stable and mostly composed of adults), survival rate (high), and home range size (reduced). These characteristics may contribute to the persistence of this species.

Caviids are usually diurnal or crepuscular and do not hibernate. They shelter in burrows that they dig or that are left by other animals. They are generally social, occurring in pairs or in groups. The population density is estimated to be 6.6 individuals/ha. Mammalian predators are absent from Moleques do Sul Island and raptors are the only potential predators.

Habitat
Areas where this species occurs are predominantly covered by herbaceous vegetation. Cavies frequently use patches with the grasses Paspalum vaginatum and Stenotraphrum secundatum, which are their main food source. The feeding areas are surrounded by bush and grass vegetation, especially Cortaderia selloana and Verbesina glabrata, which also are used as shelter by the cavies.
Distribution
This species has one of the world’s smallest geographical distributions for a mammal. It is found in an area of only 4 ha in Serra do Tabuleiro State Park, on Moleques Island do Sul, in the state of Santa Catarina, Brazil. This island itself only has a surface area of 10.5 ha.
Population Estimate
Estimated to be 24 – 60 individuals.
Population Trend

Unknown.

Status
Classified as Critically Endangered (CR D) on the 2010 IUCN Red List of Threatened Species.
Threats
The species is thought to be threatened by hunting. Both the island and protected area in which it occurs are freely accessible and enforcement is not strict. The species’ small population size and range make it particularly vulnerable to threats.
Conservation Underway
Occurs in Serra do Tabuleiro State Park which may receive funds from the Global Environment Facility (GEF) for the conservation of biodiversity and ecosystem rehabilitation. The species’ habitat has been designated a Preservation Zone, and all entry is prohibited. However, this park is unmanaged and the park status and entry prohibition are not enforced.
Conservation Proposed
Enforcement of the Preservation Zone that encompasses this species’ range needs to be accomplished.
References
Chapman, R.E. 2008. Cavia intermedia. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. <www.iucnredlist.org>. Downloaded on 15 November 2010.

Cherem, J. J., Olimpio, J. and Ximenez, A. 1999. Descricao de uma nova espcie do genero Cavia Pallas, 1766 (Mammalia - Caviidae) das Ilhas dos Moleques do Sul, Santa Catarina, Sul do Brasil. Biotemas 12: 95-117.

Nowak, R. M. 1999. Walker’s Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Salvador, C. H. and Fernandez, F. A. S. 2008. Reproduction and growth of a rare, island-endemic cavy (Cavia intermedia) from southern Brazil, Journal of Mammalogy. 89(4): 909-915.

Salvador, C. H. and Fernandez, F. A. S. 2008. Population Dynamics and Conservation Status of the Insular Cavy Cavia intermedia (Rodentia: Caviidae). Journal of Mammalogy, 89(3): 721–729

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