Mauro is the leader of a group of mischievous Common Marmosets who steal from the tourists of Rio de Janeiro, and are experts in Capoeira. He and his minions are forced to work for Nigel and obey all of his orders. He is voiced by Francisco Ramos in Rio.
After a busy day of stealing from tourists (via Mauro performing dance moves to entertain them while the others loot the tourists' bags and pockets for valuables), Mauro and his group of marmosets are seen dancing at their hangout until they are approached by Nigel, who demands that they help him in finding Blu and Jewel. When Mauro asks the angry cockatoo what is in it for them, Nigel carries the marmoset up to a great height and drops him. The terrified Mauro begs the cockatoo to save him. After Mauro promises that he and his gang will help, Nigel catches Mauro when he is a few inches away from crashing into the ground. Mauro and his henchmen are then ordered by Nigel to find Blu and Jewel by the end of the day, under the threat of "flying lessons for everyone".
Mauro's minions find the blue macaws, Blu and Jewel, at the Samba Club, and Mauro leads the marmosets in confronting the macaws. Mauro says, "You two are coming with me". Then Jewel retorts, "In your little monkey dreams", and spits at Mauro's foot. After engaging in battle with them and their bird friends, Mauro and his minions lose both the fight and their quarry, plus some of the marmosets are knocked out in the fight. A dazed Mauro is later manhandled by Nigel for failing and says, "Papa?" Then, when Mauro gets up, Nigel throws Tiny at him, knocking him out.
After Nigel is reduced to a featherless mess due to his accident (from a plane crash), Mauro gains his revenge by laughing hysterically and taking a picture of the humiliated and plucked cockatoo.
- He and his minions were dancing to distract tourists so they could steal their belongings.
- He can command the marmosets to steal tourists valuables and follow his orders.
- Mauro knows how to use a cell phone to track Blu and Jewel. He also uses a vibration on a chair for fun.
- The marmosets captivate the tourists with their dance moves in order to sneakily steal belongings such as cameras, rings, cell phones, iPods, watches, jewelry, food, and clothes.
- Mauro is the only marmoset that is identified by name and color. He has brown colored fur, and his henchmen are gray. The only thing that is the same is the black stripes on their tails and white tufts of fur on their heads. In addition, he has extra white fur on his scalp with a paper clip, while his minions have none of those features. He also has green eyes while his henchmen have brown eyes. He also the marmoset shown speaking in full sentences as none of the others are shown speaking for unknown reasons aside from one saying "giddy-up" at the Samba Club battle when on top of an unnamed bird.
- When Rio was being promoted, McDonald's Happy Meal toy promotions mistakenly said that Mauro was one of the characters that came as a toy, but the toy monkey does not exactly resemble Mauro.
- Instead, it resembles more like a member of his henchman, due to the toy figure being gray and not having an extra bunch or a paper clip.
- Mauro's name was never mentioned in the film. He was listed in the credits as "Lead Marmoset". His name is revealed in the video game.
- Mauro was called "Little King Kong" by Pedro.
- In Angry Birds Rio, Mauro and the other marmosets are shown as being "official" minions of Nigel.
- In the junior novel, Mauro wears a coat stuffed with stolen valuables, making him look bigger than he actually is.
- "What, this?"
- "This is just some stuff we...found."
- "Right, boys?"
- "Oh yeah!"
- "What's in it for us? laughs"
- "Save me, save me!"
- "We'll do it! We'll do it! Save me please!"
- "Save meeeeeee!"
- "We got 'em."
- "You two are coming with me."
- "This isn't your fight, big nose!"
- "Get them!"