A real invasion, as reported by Argentine media about two years ago. About 400 capybaras (Hydrochoerus hydrochaeris) have been spotted roaming freely in Nordelta, one of Buenos Aires Province’s wealthiest neighborhoods. Capybaras are the world’s largest rodents, capable of reaching around 1.3 meters in length and weighing up to 65 kilograms. These animals, which had long lived among neighbors, multiplied quickly and began to cause havoc: they clashed with cats and dogs, created traffic hazards, and damaged green spaces. Their urban presence is boosted by an extraordinary ability to eat whatever is available, allowing them to thrive in city environments.
An article in a zoology journal highlighted this species dietary flexibility, noting capybaras’ widespread presence in many cities around the world. In their natural habitat they roam grasslands, wetlands, and river systems in South America. Although they are herbivores, their diet is not limited to plants alone; they can adapt to a broader range of foods when necessary.
Capybaras left dense grasslands and began to inhabit garden areas of some cities, making room for themselves in urban spaces. São Paulo, Brazil’s largest metropolis, provides another example where capybaras have taken up residence around university campuses. They also navigate trails and crop fields, taking advantage of high calorie crops when available.
Brazilian capital specimens helped explain this unprecedented urban invasion. Marcelo Maglioli, an ecologist at the University of Sao Paulo and the National Center for Research and Conservation of Carnivorous Mammals (CENAP), led a study examining the plumage and feeding patterns of capybaras from 13 population groups across the country. The team analyzed stable carbon isotopes to determine the mix of natural and human-influenced foods in their diet.
They eat everything and adapt to everything
Findings show that capybaras’ diet flexibility has enabled them to survive in places far from lush tropical forests and in landscapes carved by roads, agriculture, and other human changes over the past five decades. While grasses and tropical plants remain common staples, capybaras that settle near farmland readily consume maize or sugarcane. In urban zones they favor shrubs, trees, vines, and even some cacti.
Our study provides clear evidence of the capybaras’ feeding flexibility in different environments. This adaptability is what helps the species survive and even thrive in both natural areas and landscapes altered by humans. Maglioli notes how striking it is that these animals can switch from preferred foods to less preferred ones to endure in nearly any habitat, a point highlighted in Science News.
Although this flexible diet supports adaptation, it does come with downsides. The study warns that capybaras feeding on crops tend to gain excess weight and may suffer health issues as a result.
Many problems for the population
In agricultural areas, capybaras are increasingly seen as a nuisance, sometimes causing more accidents as they dart between vehicles. In major cities their presence raises concerns about disease transmission, since ticks that infest capybaras can carry diseases that affect humans. Experts emphasize the importance of reconnecting fragmented habitats to allow natural predators to help regulate capybara numbers, reduce human contact, and restore ecological balance.
What is a capybara? A capybara, or capybara proper, is a large rodent native to South America. It is the largest living rodent in the world, reaching up to about 1.3 meters in length and up to 65 kilograms in weight. The only other living member of its genus is the smaller capybara, Hydrochoerus isthmius. Close relatives include guinea pigs and coypus, with more distant ties to the agouti and chinchilla. Capybaras inhabit wetlands and dense vegetation near bodies of water. They are highly social, typically found in groups of ten to twenty, though herds can number up to a hundred individuals. They are hunted for meat, skin, and the oil extracted from their fur.
Referenced work: zslpublications.onlinelibrary.wiley.com/doi/10.1111/jzo.13057