Humans have translocated thousands of species of flora, fauna and microorganisms to places they would never have reached on their own. Non-native species may have effects on biological communities, ecosystem functions and human populations. In island environments, the effects of spreading non-native species on native biodiversity can be severe and lead to native ecosystem transformation and even endemic species extinction. The Galapagos Islands are a region of particular interest and relevance to the issue of species introduction and invasiveness. In this paper, I analyse the current status of 25 non-native amphibians, reptiles and birds that have been reported in the Galapagos Islands. Six species have established self-sufficiently in Galapagos and may become invasive: Fowler’s snouted tree frogScinax quinquefasciatus, common house geckoHemidactylus frenatus, mourning geckoLepidodactylus lugubris, dwarf geckoGonatodes caudiscutatus, Peters’ leaf-toed geckoPhyllodactylus reissii, and smooth-billed aniCrotophaga ani. Domestic fowlGallus gallus holds feral populations, which may have self-sufficient populations, but evidence is unclear. I provide information on the distribution and natural history of non-native species of amphibians, reptiles and birds in Galapagos, including new data about the introduction history ofS. quinquefasciatus; evidence on the establishment ofH. frenatus on Isabela and San Cristobal islands; the first published record of a non-native snake in Galapagos,Lampropeltis micropholis; the first evidence of predation on squamate reptiles byG. gallus in Galapagos; and evidence of a probable major impact byC. ani due to extensive predation on the endemic Galapagos carpenter beeXylocopa darwini. I comment on the invasiveness and impact potential of non-native species in Galapagos, identify vulnerable islands for the arrival of non-native species, identify potential hitchhiker that could arrive in the future and propose that it is important to rethink about how we understand, manage and prevent introductions of non-native species. The new wave of introduced species in Galapagos is formed by small hitchhikers, species that are easily overlooked, may travel in high numbers and are highly linked to human-made environments.

This is a preprint submission to PeerJ Preprints. This manuscript contains novel information on non-native small vertebrates occurring in the Galapagos Archipelago. A version of this manuscript was submitted to a book. This manuscript contains complete information for all data, and it will serve as reference to other papers about non-native biodiversity in oceanic islands.