There are two species of marmosets native to Brazil, but illegal trafficking threatens to put them on the brink of extinction.

The black-tufted marmoset (Callithrix penicillata) is known as micro-estrels in Portuguese and native to Brazil’ carrado biome; and the common marmoset (Callithrix jacchus) is originally from the Brazillian northeast. Both of them were trafficked in large numbers in the 1980s and 1990s are people considered them as “pets.”

“These two species are common on the Southeast today. Even though trafficking may not have led to the release of so many in nature, those that were introduced multiplied in absurd numbers,” said Fabiano Melo, professor in the Forestry Engineering Department at Vilosa Federal University in Minas Gerais state.

Those purchased as pets largely ended up being abandoned in forested areas close to large urban centers where they most likely multiplied.

Although this may sound like good news, the problem is there were already two endemic species of marmosets in the Southeast, both of which were listed as threatened by the IUCN Red List. The buffy-tufted-ear marmoset (Callithrix aurita) is native to Sao Paulo, Minas Gerais, and Rio de Janeiro, and is considered an endangered species, while the buffy-bearded marmoset (Callithrix flaviceps) from the states of Minas Gerais and Espirito Santo is critically endangered.

The introduction of invasive animals creates an imbalance. “The invasive marmosets are expert predators and eat many bird eggs and hatchlings. The native species must have been having quite a difficult time,” Melo said.

Most marmosets have been trafficked when they were young becuade they look cute to people’s eyes. But once they grow up, those who purchased the animals realized they have undesirable traits that soon become unbearable, so they release them into nearby forests. What they don’t know is the abandoned marmosets create an imbalance thay endangers the endemic species.

“No one has taken southeastern marmosets to the other biome. In fact, it would be difficult for them to survive there. They are adapted to the coastal atlantic rainforest, which is more humid and offer more food,” Melo explained. “The invasive marmosets do well in the southeast because they are from the Cerrado and Caatinga, which are more hostile environments.”