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Ronnie, Donnie, and Lonnie are three egg-stealing Monitor Lizard brothers. They first appear in The Great Swamp Search​​​​​​, as one of the three Invasive Species Ranger Marsh was searching for. They're the second Invasive Species caught in the episode.

When we first meet them, they're shown spying on a group of sleeping gators, and we learn of their plan to steal one of the "Little green wiggly things" (baby gators). When Kwazii attempts to stop them, they use their tail whips to attack him, awakening the gators, who believe Kwazii's trying to attack them. This disctracts them long enough for them to get ahold of one of the babies and escape, unnoticed. Barnacles and Tweak go after them, to get the baby back, but whilst they're successfull in retrieving it, it's only when Marsh catches the trio with a trap, that they're caught. To componsate for the baby gator, they're given Fish Biscuits, which manages to satsify their hunger. After the episode, they're returned back to The Nile River in Africa.

The brothers would go on to return in Above and Beyond Season 2, as apart of The Monitor Lizards episode, alongside Spiny Sue. Where Ranger Marsh revisits them, only to find Ronnie alone, as Donnie and Lonnie had wondered off, with Ronnie fearing that they could be lost. Shellington is sent out to help Marsh reunite the brothers, not before having Ronnie return a Waxbill egg he had stolen from a Whydah nest and almost ate. The three eventually find Donnie, trying to snag a crocodile egg from a nest being protected by some Water Dikkops, and Lonnie, hiding in a tree, as they chase some Baboons, who stole one of the eggs. Throughout the episode, Ronnie shows signs, he wants to be back in the Everglades, heavily indicated by when he tells Shellington and Ranger Marsh that he believes he and his brothers were better off living there. But by the end of the episode, he comes to understand that Africa is where he and his brothers truly belong, as the three happily reunite, and scare some Lions off with their tail whips.