Cavia intermedia

Geographic Range

Cavia intermedia has the smallest known geographic range of all mammalian species. Moleques do Sul guinea pigs inhabit a mere 4 ha (about 40,000 square meters) area of the Serra do Tabuleiro State Park on the archipelago of Moleques do Sul, Santa Catarina, Brazil. The 10.5 ha (105,000 square meters) island is the only known area where C. intermedia is native. This isolated species is thought to have diverged from the closely related Cavia magna approximately 8,000 years ago when rising sea levels separated the archipelago from the mainland.

• Biogeographic Regions
• neotropical neotropical
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

Moleques do Sul guinea pigs occur mainly in the grasslands of the island as opposed to the rocky deserts of the extreme southwest. The total vegetated area of the Moleques do Sul archipelago encompasses approximately 6.4 ha; however, C. intermedia prefers to inhabit an area covered in herbaceous vegetation such as Paspalum vaginatum and Stenotraphrum secundatum , its preferred food sources, which only covers 0.77 ha. Grass ( Cortaderia selloana ) and bush ( Verbensia glabratta ) vegetation surround these feeding areas and serve as shelter for the cavies. This habitat has a humid mesothermal climate, with hotter weather in the summer, rainfall throughout the entire year, and reduced precipitation during the winter months.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

Physical Description

Moleques do Sul guinea pigs have long, coarse fur, usually gray or brown in color, with longer hair at the neck. They have stocky, cylindrical builds with no external tail, short limbs, and short, hairless ears. The four digits on each forefoot and three digits on each hind foot are armed with sharp, grasping claws. Like other species of rodents, they have continuously growing teeth that are kept at an appropriate length by the grinding of their herbivorous diet. Unlike other species of cavies , Moleques do Sul guinea pigs do not show sexual dimorphism in adult body mass. Adults of both sexes have a similar average body mass ranging from 495 to 750 grams. Young cavies have a body mass less than 400 g and sub-adults have a body mass between 400 and 500 g.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

Although mating systems in C. intermedia have not been extensively studied, these cavies exhibit reproductive behaviors that are similar to those of their close relative greater guinea pigs . The mating systems of greater guinea pigs include monogamy, promiscuity, polygyny, and polyandry. To further study this diversity, behavioral strategies of females were reviewed. For example, estrous females actively seek to reproduce with several males to prevent a single male from monopolizing mates (Adrian & Sachser, 2011). Also, the spacing behavior exhibited by cavies supports the idea of this reproductive diversity, particularity promiscuity. Female ranges overlap with those of other females along with male territories. Male territories are larger than those of females, yet these territories also overlap with rival males. Such unpredictable female locations may prevent males from monopolizing females spatially. This spatial behavior in wild cavies explains a more solitary mating system which is best described by promiscuity.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Unlike other species of Cavia that have spring and summer reproduction periods, C. intermedia individuals reproduce year round. This continuous breeding pattern allows the species to have multiple litters and increases recruitment rates. Much like other cavies , C. intermedia has a gestation period of about 60 days and is likely to conceive postpartum. The weaning period, as observed in other wild cavies , is less than 30 days. Cavia intermedia also displays reproductive behaviors supported by the island syndrome. These traits include small litter size (1 to 2 offspring) and delayed sexual maturation (about 59 days).

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous
• post-partum estrous

Since their recent discovery in 1999 (Cherem 1999), parental investment in Moleques do Sul guinea pigs has not been extensively studied. Close relatives of these guinea pigs show rival parental investment. Parental care in great cavies , which shows promiscuous mating systems and solitary behavior, tends to be female-dominated. Mothers provide for and protect their young (usually 1 or 2 per litter) until they reach independence (about 30 days). Brazilian guinea pigs are polygynous, with 1 to 2 females mating with a single male. In this small group, paternity of offspring is known and males invest time in their young by providing protection. Neither parent is involved after the offspring reach independence (about 30 days).

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

Lifespan/Longevity

The lifespan of Moleques do Sul guinea pigs has not been thoroughly observed. Salvador and Fernandez (2008) found the maximum longevity in their study to be lower than they expected for an insular population. The longevity of the island population showed to be as short as in other species of Cavia . The expected life span of great cavies is between 2.4 and 16 months in the wild or 8 years in captivity (Kraus et al. 2005), the difference due to mammalian predators. However, Moleques do Sul guinea pigs do not have mammalian predators on Moleques do Sul island, and only a few species of raptors present on the island have shown to be effective in the predation of wild cavies. The length of the study (17 months) also constrained the maximum life span of that could be recorded. Recorded longevity was based on the number of days between first capture and last capture of an individual, this was up to 363 days.

Behavior

Behaviors of Moleques do Sul guinea pigs have yet to be studied more extensively since the first study in 1991 (Olimpio 1991). In general, cavies tend to be diurnal or crepuscular. Like other neotropical rodents, they do not hibernate. They shelter in bushes or other vegetation or dig burrows. As social animals, they occur in groups. The population density of Moleques do Sul guinea pigs is 6.6 individuals per ha.

• Key Behaviors
• terricolous
• crepuscular crepuscular
• motile motile
• sedentary sedentary
• social social

Home Range

Moleques do Sul guinea pigs have a home range size similar to Brazilian guinea pigs and much smaller than great cavies . The small home range of C. intermedia is likely due to the island syndrome, which states that insular rodent populations will exhibit characteristics different from their continental relatives. These characteristics include a high and stable density, an age structure consisting mostly of adults, a high rate of survival, and a reduced home range size.

Communication and Perception

Communication and perception has yet to be observed or studied in Moleques do Sul guinea pigs. Related species, including continental ( great cavies and Brazilian guinea pigs ) and domestic ( domestic guinea pigs ) relatives, tend to communicate with auditory cues such as chirps, purrs, squeaks and squeals. These sounds can either communicate a threat, greeting or reproduction status to an individual. Other forms of communication that are likely used are chemical to inform males of estrous and rivals of territories. They are able to see easily in low light.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Moleques do Sul guinea pigs are folivorous, eating mainly the leaves of grasses. Of the 6.34 ha of available grassland habitat on Moleques do Sul, these guinea pigs only forage on the 0.77 ha that contain the grasses Paspalum vaginatum and Stenotraphrum secundatum .

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• flowers

Predation

Moleques do Sul is an isolated island with few vertebrate inhabitants, which include 31 species of birds and an undescribed species of worm lizard in addition to C. intermedia . Raptors, including southern caracaras ( Caracara plancus ), yellow-headed caracaras ( Milvago chimachima ) and Chimango caracaras ( Milvago chimango ), are the only known predators of C. intermedia (Kraus 2004). Burrowing owls ( Speotyto cunicularia ) and peregrine falcons ( Falco peregrinus ) were not observed on the island during the study (Salvador & Fernandez, 2008), but may be additional predators.

Anti-predator adaptions have not been studied in Moleques do Sul guinea pigs. However, their dull brownish/gray coat likely helps camouflage them from aerial predators in their grassland habitat.

The domestic relative of Moleques do Sul guinea pigs, domestic guinea pigs , use two strategies to escape predation. These two defense mechanisms are known as the "immobility response" and the "scatter response." In the former, an individual encountering a threat will remain immobile until that threat is gone; in the latter, a group of cavies encountering a threat scatter in an attempt to confuse and disorient their predator.

Ecosystem Roles

There is little information known about the roles Moleques do Sul guinea pigs play in their ecosystem. They inhabit Moleques do Sol island with 31 species of bird and an undescribed worm lizard of the family Amphisbaenidae . The grasses on Moleques do Sul tend to be only 5 cm in length compared to 15 cm in length on neighboring islands of the archipelago, possibly as a result of C. intermedia grazing. This also suggests that population density should be dependent on resource availability and predation. However, Moleques do Sul guinea pigs have few predators whose diet consists solely of cavies and there is no correlation between population density and seasons in which resources are scarce or readily available. These data suggest that they are not a keystone species. However, no conclusions can be drawn without additional information.

• Ecosystem Impact
• creates habitat

Economic Importance for Humans: Positive

Moleques do Sul guinea pigs are hunted by locals. Free accessibility, lack of enforcement of protected areas by the state of Santa Catarina, and their small geographic range make them easy to hunt. The small geographic range of Moleques do Sul guinea pigs, small population size, and unique chromosomal number compared to other species of Cavia (Gava et al., 1998) - as well as its conservation status - proves to be an interesting subject of research and a possible focus for conservation-based education.

• Positive Impacts
• food food
• research and education

Economic Importance for Humans: Negative

Because the geographic range of C. intermedia does not overlap with any human inhabited ranges, there are no known adverse effects of Moleques do Sul guinea pigs on humans.

Conservation Status

Moleques do Sul guinea pigs are classified as critically endangered by the 2010 IUCN Red List of threatened species. Their small geographic range and low population numbers make it particularly vulnerable to threats, which are thought to be primarily hunting-related due to the free accessibility and lack of enforcement of protected areas on the island. Conservation methods have been proposed to enforce the preservation zones that cover this species' range and receive funding from the Global Enforcement Facility (GEF) for the conservation of biodiversity and ecosystem rehabilitation since C. intermedia occurs in the Serra do Tabuleiro State Park.

Other Comments

Moleques do Sul guinea pigs, which are endemic to a 10.5 ha island in the Moleques do Sul archipelago, has the smallest geographic range of all mammalian species and one of the smallest populations. Population estimates range from 24 and 60 individuals.

Additional Links

Encyclopedia of Life

Contributors

Katelyn BaDour (author), University of Wisconsin - Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Tanya Dewey (editor), University of Michigan-Ann Arbor, Shaina Stewart (editor), University of Wisconsin - Stevens Point.

References

Adrian, O., N. Sachser. 2011. Diversity of social and mating systems in cavies: a review. Journal of Mammology , 92(1): 39-53.

Asher, M., E. Spinelli de Oliveira, N. Sachser. 2004. Social system and spacial organization of wild guinea pigs (Cavia aperea) in a natural population. Journal of Mammology , 85(4): 788-796.

Chapman, R. 2013. "Cavia intermedia" (On-line). IUCN Red List of Threatened Species. Accessed August 23, 2012 at http://www.iucnredlist.org/details/summary/136520/0 .

Hixon, J. 2011. "Cavia porcellus" (On-line). Animal Diversity Web. Accessed August 23, 2012 at http://animaldiversity.ummz.umich.edu/accounts/Cavia_porcellus/ .

Kraus, C., J. Kuenkele, F. Trillmich. 2003. Spacing behaviour and its implications for the mating system of a precocial small mammal An almost ascocial cavy Cavia magna?. Animal Behavior ust , 66(2): 225-238.

Salvador, C., F. Fernandez. 2008. Population dynamics and conservation status of the insular cavy Cavia intermedia (Rodentia: Caviidae). Journal of Mammology , 89(3): 721-729.

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

Zoological Society of London. 2010. "Santa Catarina's Guinea Pig (Cavia intermedia)" (On-line). EDGE: Evolutionary Distinct and Globally Endangered. Accessed August 23, 2012 at http://www.edgeofexistence.org/mammals/species_info.php?id=1412 .