They are very common throughout Puerto Rico , where they are collaquially known as `` Gallina de palo '' and considered as an invasive species introduced from South America ; in the United States feral populations exist in South Florida ( including the Florida Keys ) , Hawaii , and the Rio Grande Valley of Texas .
The green iguana ranges over a large geographic area , from southern Brazil and Paraguay as far north as Mexico and the Caribbean Islands especially in Puerto Rico where they are also known as `` Gallina de palo '' and they are very common throughout the island where it is seen as an intruder animal from South America ; and in the United States as feral populations inSouth Florida ( including the Florida Keys ) , Hawaii , and the Rio Grande Valley of Texas .