Invasion records of a lizard and new cases of reptile introductions on the archipelago of Fernando de Noronha, northeast Brazil

Abstract

Invasive vertebrates are a primary cause of biodiversity loss on islands. The Fernando de Noronha archipelago in the South Atlantic is highly vulnerable, with a history of exotic species introductions. While previous studies have documented introductions, the establishment status of some species remains uncertain. This study documents the invasion of the lizard Tropidurus hispidus on the main island, updating its status from ‘unknown’ to ‘established’. We compiled 20 records of T. hispidus from 2019 to 2025, including a 2024 observation of a group of individuals of different ages that indicate a reproducing population. The lizards are now widespread, particularly along the northern coast. This establishment may pose a potential threat to native reptiles through competition or disease transmission. Herein, we report novel cases of exotic reptile introductions, including a broad-snouted caiman (Caiman latirostris), a Geoffroy’s Sidenecked Turtle (Phrynops geoffroanus), tortoises (Chelonoidis sp.), and a green snake (Erythrolamprus viridis). Combined with previous data, these findings show that 50% of the exotic amphibian and reptile species introduced to Fernando de Noronha have established invasive populations. This high establishment rate underscores the acute susceptibility of tropical islands to biological invasions and highlights the critical need for robust surveillance and rapid response protocols to prevent further introductions and mitigate impacts on this fragile ecosystem.