A pair of capybaras, the largest known rodents in the world, was filmed entering the Legislative Assembly of Mato Grosso in southwestern Brazil and have since gone viral throughout the week for their nonchalant enjoyment of the building’s lobby.
The incident reportedly occurred on Thursday, July 30, and was filmed by legislature employee Diego Peralta, who told the local newspaper Diario de Cuiabá that the rodents live in a park across the street and walk over to the legislative grounds every evening to feed on grass and peruse the landscape. They do not commonly enter the building, however, and appeared to walk out without incident after observing the building lobby and finding nothing of interest to them.
The Mato Grosso state assembly is located in the city of Cuiabá, which is believed to have one of the world’s largest populations of urban capybaras as it is located near the Pantanal wetlands, where the animals make their home in large numbers. The urban capybaras live in the city, however, and feed on grass and water plants. They are not believed to travel commonly in and out of the city to the wetlands, as the city provides shelter from predators and the extreme heat of the Brazilian summer.
In its initial report last week on the capybara legislative invasion, the Diario de Cuiabá observed that the animals “had already been seen crossing the pedestrian crossing in front of the Assembly and circulating through the complex’s fountain, where they usually fetch water to relieve the heat.” The newspaper appeared amused in an update on Wednesday that the images had become an international topic of discussion given how common capybaras are to life in the region.
Speaking to Peralta, the employee who recorded the video, the newspaper noted that the rodents perused the lobby “in complete tranquility” and, “as they were unable to enter [the lawmaking chamber], the animals stopped walking and remained in place.”
Peralta said that he sees the animals every late afternoon walk over from the Parque das Águas across the street, which contains a small body of water that satisfies their need for a semi-aquatic environment. The animals reportedly enjoy the reflecting pool on the premises of the legislative building and grass surrounding it.
Capybaras are indigenous to South America and extremely common in cities near large marshes. While mild-mannered, vegetarian, and often friendly to humans, the rodents’ large size makes them a potential threat to children if they feel the need to attack and may cause conflict with cars. Capybaras can grow to be as long as 4.5 feet and two feet tall, and weigh up to 150 pounds. The average capybara weighs about 108 pounds.
The Diario de Cuiabá reports somewhat regularly on capybara encounters, given how common they are in the city. In July, for example, the newspaper reported on a video of a family of capybaras crossing André Maggi avenue, a multi-lane thoroughfare in the city. The animals appeared to watch for traffic to stop before crossing, leading some online to joke that humans could learn traffic safety from them.
While capybaras themselves are not considered a particular threat to humans, they are carriers of parasites that present a significant disease risk, particularly ticks.
“The high rate of animals such as the capybara also favors an increase in the population of parasites, such as ticks,” Adriana Borsa, the deputy director of the Faculty of Veterinary Medicine at the Federal University of Mato Grosso (UFMT), told the Gazeta Digital in March 2024. The report mentioned that the capybaras were already a common sight in the Mato Grosso Legislative Assembly’s reflecting pool. “This tick may be contaminated with a microorganism that transmits spotted fever. We have not yet recorded any cases in our region, but in the southeast there have already been deaths due to the disease.”
Borsa recommended that individuals in areas with capybaras not sit on grass in parks and be diligent in looking for ticks on their person or their pets when they leave the park.
Capybaras appear to have become increasingly common in urban spaces in part due to the destruction of their natural habitats and farmland, but also because they have what Borsa described as “resistance to levels of pollution”; they do not appear to mind city living as much as other animals native to the area.
Outside of Mato Grosso, in Santa Catarina, the city of Florianópolis has seen a significant increase in the local capybara population in the past decade. They first began making their appearance there around 2007. As Florianópolis is on an island, experts believe the animals swam over from the mainland. Scientists noted that their arrival did not necessarily mean that the city had become less polluted as this factor has not seemed to deter capybara populations in other cities.
The animals cause some issues with traffic and pose a not-insignificant public health threat, but as a Brazilian national treasure, they are protected by law. As Courthouse News explained in 2025, municipal governments cannot independently pursue capybara population control without checking with state and federal environmental agencies.
“The law protects capybaras, and that’s becoming a challenge for cities,” environmental lawyer Felipe Neves Linhares told the outlet. “In my view, municipalities should have greater autonomy.”
The Federal University of Mato Grosso (UFMT) paired up with the city of Cuiabá in 2022 to launch a program to monitor and study the city’s capybaras, including a capybara census and explorations of how they live, their social ties, and their environmental preferences in the city.