Capybaras, the world’s largest rodents, are native to the vast grasslands, wetlands, and rivers throughout South America. As their name suggests, they are known for their grass-eating habits. However, researchers have recently found that the rodents are not picky eaters and can adapt to different diets. Their flexible diet has helped them to adapt to human-modified environments.
The new findings, which appear in the Journal of Zoology, suggest that dietary flexibility has helped capybara populations grow in cities and survive in far-flung landscapes that have been fragmented by human-made changes over the past few decades. Capybaras seem to be equally happy munching on leafy forest plants as they are eating the wavy grasses they are used to. This has allowed them to expand their population and adapt to different environments.
Maria Luisa Jorge, an ecologist at Vanderbilt University in Nashville who was not involved in the study, stated, “If a species’ diet is pretty specialized, that’s going to constrain their ability to adapt to modified ecosystems. Capybaras eat a lot of grass – we call them grazers – but they can eat other things. That has set them up for success.”
São Paulo, Brazil’s most densely populated metropolis, is a prime example of the capybara’s ability to thrive in a human-modified environment. Marcelo Magioli, an ecologist at Instituto Pró-Carnívoros in Brazil, noted that capybaras can be seen every day grazing on campus lawns. They also wander along roadways and frequent farm fields, which give them access to calorie-rich crops. The research team sampled hair from 210 capybaras in 13 different populations living in natural to heavily modified environments around Brazil to determine what capybaras were eating to survive the shifting landscape.
The researchers analyzed carbon isotopes, which can act as chemical fingerprints, in capybara hairs. The carbon isotopes helped the scientists determine how much grass versus forest plants the animals ate. As expected, capybaras with access to crops were eating them up; corn and sugarcane are grasses, familiar foods for the rodents. However, capybaras in more fragmented, urban areas, and in the Pantanal, where forests are encroaching into grasslands, were found to munch on trees, vines, and even cacti that were available to them, rather than selectively searching out grasses.
Magioli stated, “I think the most impressive feeding behavior of this species is that they can transition between preferred and nonpreferred foods so they can survive in practically any habitat.”
While the flexible diet might mean capybaras have survived some significant ecosystem changes, it’s not all good news. Crop-eating capybaras can get too chunky and suffer poor health, as well as be viewed as pests by farmers for eating or damaging crops. Comfort around infrastructure means more get hit by cars, and ticks the rodents carry can transmit deadly Brazilian spotted fever to humans.
Reconnecting fragmented landscapes could let natural predators control capybara populations, decrease contact with humans, and restore an ecological balance, Magioli says.
Capybaras are an incredibly versatile species that can thrive in various environments. Their dietary flexibility has played a significant role in allowing them to adapt to human-modified environments. The capybaras’ ability to transition between preferred and non-preferred foods has allowed them to survive in practically any habitat. However, it is important to note that capybaras can pose problems in heavily human-modified areas.