Alligators bite plastic bags in search of food in the west zone of Rio

Water pollution in Recreio dos Bandeirantes, in the west zone of Rio de Janeiro, is affecting the caimans that live in the area. In the canals that run through the neighborhood, used by the animals to move between streets and residential complexes, they coexist with accumulations of illegally discarded waste.

The caimans swim among debris and bite into plastic bags in search of food along stretches of the Canal das Taxas, a waterway that flows into Marapendi lagoon, part of the lagoon complex of Barra da Tijuca.

In April of this year, in one section of the canal, a specimen was chewing on a plastic bag that covered part of its snout as it attempted to reach food scraps. In total, more than ten caimans were spotted amid bottles, drums, packaging, and even a ball in an area near the intersection of Avenida das Taxas and Avenida Gilka Machado.

At the end of June, researchers returned to the site and the animals were still there.

Contacted by phone and email, the Municipal Secretariat for the Environment did not directly address the case, but stated that responses to incidents involving wild animals in situations of risk are handled by the municipality's Environmental Patrol.

The department also stated that Comlurb (the Municipal Urban Cleaning Company) is responsible for removing waste from the banks of the Canal das Taxas, Canal de Sernambetiba, and Canal do Cortado — the three canals in Recreio dos Bandeirantes — when the presence of caimans does not impede the work, in addition to supporting cleanup efforts carried out by other agencies.

Due to irregular waste disposal and territorial limitations, the presence of caimans amid garbage is frequent in the west zone of Rio, according to veterinarian Flavio Fernando Batista Moutinho, a professor at UFF (Fluminense Federal University) and specialist in animal collective health.

He stated that the movement of broad-snouted caimans is common in Recreio dos Bandeirantes and other neighborhoods in the west zone, such as Barra da Tijuca and Jacarepaguá, which were built on wetlands between the sea and the lagoons.

In the first half of this year alone, there were 312 captures and rescues of caimans in the state, according to the State Military Fire Brigade. This figure is 131% higher compared to the 135 cases recorded in the same period last year. The number also surpasses the 256 cases accumulated throughout all of 2025.

These cases include calls from residents reporting animals that had moved from bodies of water into residential areas following periods of heavy rain or flooding, sightings near homes and schools, and cases involving illegal breeding.

According to Moutinho, the improper disposal of organic waste and garbage can cause changes in the feeding habits of caimans.

"Since we don't have a perfect waste collection system, and many people have the habit of putting garbage in the wrong place, on the wrong day and at the wrong time, the caimans end up coming to eat garbage as well, drawn by the smell," the professor said. "They look for food where it is easiest to find. Once they get used to eating garbage, they go back to where they already know it can be found."

In May of this year, the rupture of an eco-barrier installed in the canal caused some of the retained waste to advance toward the Lagoinha das Taxas, located within the Chico Mendes Municipal Natural Park, one of the sites where rescued caimans from the area are taken.

Part of the waste was held back by a second barrier. The damaged structure was subsequently repaired and the material collected by Comlurb, with support from teams from Fundação Rio-Águas, the municipal company responsible for water services.

Residents of the area said there are cases in which caimans pass under the trash containment barrier and end up returning to the canal, remaining in areas close to the accumulated waste.

Habitat reduction

Neighborhoods such as Recreio dos Bandeirantes, Barra da Tijuca and Jacarepaguá have developed and attracted new residents in recent decades with the construction of housing — particularly large condominium complexes — as well as mobility and infrastructure projects in areas previously occupied by native vegetation.

As a result, the caimans living in the region have come to face a reduced, dirtier habitat with fewer hunting options.

"You start occupying natural spaces with condominiums, housing developments and buildings, and you reduce the living space of these caimans. By reducing that space, you also reduce the area available for natural feeding and their interaction with the environment they are accustomed to," said Moutinho.

Caimans spend most of their time in the water, but venture onto dry land to bask in the sun and regulate their body temperature, build nests and move around.

Biologist Ricardo Freitas Filho, founder of Instituto Jacaré, which specializes in the management and rescue of wildlife in urban areas, said that caiman rescue cases in Rio's West Zone are frequent.

In early June, he took part in the capture of three adult caimans and the release of three hatchlings found near a development in the area. The animals were returned to different points of Jacarepaguá lagoon.

"We released these monitored caimans into a specific nursery area with animals of the same size and build, thereby maintaining the balance of the caiman population throughout the entire lagoon complex," said the biologist. Another nighttime operation is planned for this month.

For Moutinho, the continued degradation of areas occupied by caimans could lead, in the long term, to the disappearance of these animals. He therefore advocates strengthening environmental enforcement in protected areas to prevent unchecked real estate expansion.

Another part of the solution, according to the professor, is to improve sanitation and waste collection in the region and raise public awareness about appropriate times for disposing of waste. "This has been a struggle for many, many years, but it's still moving at a crawl."

Iguá, the concessionaire responsible for sanitation services in the region, said that dredging works are currently underway in the lagoons of Barra da Tijuca and Jacarepaguá, with completion expected in 2027. The goal is to remove accumulated sediment and increase water oxygenation.

The concessionaire added that the Canal das Taxas has a dry-weather collector in operation, which directs sewage illegally discharged into storm drains for treatment. According to the company, approximately 1.5 million liters are treated monthly through the system.