Saturday, 26 June 2010
Rodennts of Bristol 3: World's largest Guinea Pig
Two of the more popular animals in Zona Brazil, our Atlantic Rainforest section at Bristol are our two female capybaras, Daisy and Lily. The name capybara comes from Guarani, and means “master of the grasses”, a good name for the largest living rodent. They are indeed relatives of thhe common pet Guinea Pig or Cavy.
Capybaras can grow to 50kg or more, and are often common where they are found. There are two species, the common Capybara Hydrochoerus hydrochaeris and the Lesser Capybara Hydrochoerus isthmius. H. hydrochaeris is found throughout tropical South America, whereas H.isthmius only found in eastern Panama, northwestern Colombia and western Venezuela.
Capybara are highly aquatic, living a rather hippopotamus-like lifestyle, spending most of the day in the water and coming out on land to feed on waterside vegetation in the evening. Depending on hunting pressure, they may be almost nocturnal.
Capybara are quite prolific, reaching maturity in 2 years and usually producing one to four young in a litter, although litters of eight have been recorded. The young are born with eyes open and can feed on grasses within a week, although they will suckle for longer. The social structure is a herd with a single dominant male and several females plus juveniles and young.
As might be expected, Capybara have numerous natural enemies, from Jaguar to Anacondas. The relation with Caiman is interesting – although caiman will take youngsters the Spectacled Caiman which is the commonest in most of the range is too small to take adults, so adults tend to ignore each other. I doubt there is a mixed exhibit of Spectacled Caiman and Capybara anywhere, but it might be an interesting experiment.
Humans prey heavily on Capybara, because they make good food (allegedly they taste like pork), and in some parts of their range they are ranched for food. This has the double advantage of preserving wetlands and reducing farmers’ costs – they do not require expensive hay and concentrates, and their rapid growth and reproduction means that an area of wetland can produce far more capybara meat than it could beef if the land was drained.
Capybara are not classed as threatened animals, although there may be some concern over habitat loss affecting some populations of H.isthmius, and they are seen in zoos all over the world as animals of interest rather than needing captive breeding programmes. To avoid being swamped with surplus baby capybaras, Bristol does not breed from our two.
Although now found only in South America, the range of Capybara species extended into North America until the mass extinction event 11,000 years ago. The species found in the southern USA, from Florida to Mexico, was Pinckney’s Capybara Neochoerus pinckneyi, which was an even larger form reaching well over 100kg – twice the size of the surviving species. Reasons for its extinction, like the rest of the North American megafauna, are hotly debated. Larger animals often have a low reproductive rate, and it is possible that Neochoerus could not sustain the hunting pressure that the modern species can.
Capybara are easy to care for, requiring a pond with clean water and ample grazing, so they are kept widely, even by private owners in some cases. Having seen a Capybara yawn, I would not like to be bitten by one, but they are fairly placid creatures. Unfortunately, they are also quite good at escaping, and as a result they tend to make the local news.
I have seen reports that there is a small feral population in Florida, but I am not sure if that is till there. As with Burmese Pythons, escaped Capybara are certainly capable of surviving and breeding in the wild if they find suitable habitat. As such an ecologically distinctive animal, I personally have some doubts they would have a damaging effect on swamp ecosystems – which after all evolved in the presence of its very similar extinct relative. All the same, I would prefer a more controlled experiment.
For videos of live Capybara, see here: http://www.arkive.org/capybara/hydrochoerus-hydrochaeris/
(image from Wikipedia)