Around 50 capybaras—the largest rodents in the world—live near a small body of water found on the University of São Paulo's campus—Raia Olímpica.
Rowers frequent the small lake, about 2km in length and 100m wide. However, the body of water also acts as a laboratory for American veterinarian Derek Andrew Rosenfield, who is testing a vaccine that will inhibit the fertility of the giant red rodents.
Rosenfield is doing a doctorate at the USP Faculty of Veterinary Medicine, and Animal Science and his research proposes a minimally invasive way to control the capybara population. Today one of the common ways to control the rodent's population is to castrate the male mammals, which requires capturing them.
In 2013, an adventurous capybara couple left the banks of the Pinheiros river with their five kids and migrated to the small USP lake. At the end of 2015, when Rosenfield started his research, the population of capybaras had multiplied to 40 in the locale.
Despite being respected and quiet (as well as the mascot for the American Cup), the capybaras bring many problems for people who frequent the body of water. Rowers complain of running into them in the water. The rodents gnaw on wooden hooves from canoes. Their stools of feces line the banks of the water.
Also, capybaras carry many ticks (each arachnid can lay up to 8,000 eggs). There is also the risk of them crossing into the avenues that line the Pinheiros river and causing an accident.
Translated by Kiratiana Freelon