The Capybara (Hydrochoerus hydrochaeris) is the largest rodent in the world. Surprisingly (for me), while reading about this animal I learnt that there is another species found in Colombia, Panamá and Venezuela known as the Lesser Capybara (Hydrochoerus isthmius). The Capybara is native of South America where it dwells near bodies of water. It is a social animal that forms large groups (up to 100 individuals) although smaller groups are more common.
Capybaras were not new to us as we had been fortunate to see them in the past while fishing in Ita Ibaté on the Paraná River, in the Beni region in Bolivia and in the Pantanal in Brasil, apart from the occasional sightings in Uruguay. I did not consider them to be very exciting animals hence they were not high on my list of “things to see” in the Iberá wetlands. My wish list included rarer mammals such as Giant Anteaters and Manned Wolves.
In retrospect, I was really unfair and I should have considered these giant rodents as a “must see” as well! Their sheer abundance made them interesting and the fact that they showed great tolerance to us while walking, bordering on indifference, added an element of intimacy that facilitated some close encounters. The latter were not too close, as adults would bark in warning while babies would squeal before moving off. This closeness -with our help I admit- made our walks in the area much more fun and detracted from our failure to find the “specials” mentioned above.
There were capybaras all over the place, of all sizes and colours. With regards to colouring, we noted the brown hair colour of those living in the Iberá lagoon vs. the red hair of their relatives dwelling in the waterlogged savannah. Although a few theories were discussed, some of them rather eccentric, we did not come to a logical explanation for this difference. What we all agreed upon was their clear alopecia that we were informed was a kind of mange. Further reading revealed that 90% of the Capybaras in an area of the Iberá wetlands suffers from mange caused by Sarcoptes scabiei, a common form of the disease and 42% showed signs of severe infestation.
The animals were seen grazing, often doing this lying down more like herbivours than rodents They were also seen swimming alone or in groups. However, and perhaps the more interesting find was the habit of these animals to occupy almost all hollows filled with water. They seemed to enjoy being quietly immersed in water and they were really reluctant to depart from these truly private bathtubs!
Somehow you expect Capybaras to gnaw! This they may do but a bit of reading reveals that they are herbivores and selective in what they graze, choosing plants with high protein content. They have a simple stomach but a large caecum that acts as the fermentation chamber. However, their most extraordinary digestive feat is that they produce two types of faeces: individual oval balls of green olive color and another of glutinous consistency and clear coloration. Cecotrophy is the name given to their habit of eating the clear droppings as, when excreted, they are still rich in nutrients.
We did not know about cecotrophy while at Iberá but we did watch an interesting phenomenon: tadpoles feeding on Capybara pellets dropped in the water. Clearly there was still nourishment left there for the benefit of other creatures as well.
We will be back to re-inspect the droppings more carefully next time!
A FEW INTERESTING VIDEOS OF THE IBERA WETLANDS:
 Myrmecophaga tridactyla and Chrysocyon brachyurus respectively.
 María J. Corriale, M.J., Orozco, M.M. y Ignacio Jiménez Perez, I. (2013). Parámetros poblacionales y estado sanitario de Carpinchos (Hydrochoerus hydrochaeris) en lagunas artificiales de los Esteros del Iberá. Mastozool. neotrop. vol. 20 no.1 Mendoza.