Escapes and deliberate releases have been responsible for the occurrence of feral populations non-native amphibians and reptiles in Britain, ranging from Midwife Toads to Aesculapian Snakes. Tropical and sub-tropical species sometimes escape in heated, indoor accommodation but rarely in sufficient numbers to produce a breeding population. However, it does happen, as a recent paper illustrates.
Two feral populations of gecko have been found in buildings at the University of Hull and the University of Nottingham. The date when they were first noticed seems to be the late 1990s-early 2000s in Hull and the 1970s in Nottingham. Both populations have been identified as Hemidactylus turcicus, the Mediterranean House Gecko or Turkish Gecko, which, as its names implies is found in countries bordering virtually the entire Mediterranean coast. It is, like many geckos, nocturnal. However, like some others in the genus, it is now to be found found in other parts of the world where it has been introduced, probably in shipments of goods. It is, for example, found in the USA and Mexico and said to be abundant in Florida.
Molecular genetic studies suggested the Nottingham population is derived from a single or very few founding individuals. Those studied from the Hull population showed greater genetic diversity, suggesting a larger number in the founder population and/or evolution in situ.
The authors speculate that the two populations were established by individuals being kept by people as part of research projects. It may be that the individuals involved are known—or could be guessed—at one site or the other but ‘no names, no pack drill’ may apply.
In Britain, it is difficult to imagine sub-tropical or tropical reptiles becoming established in buildings, other than in those heated all day, every day, in the winter in the decades before the 1970s. Laboratory buildings were often freezing cold in vacations and at weekends—far too cold for most reptiles to survive let along breed and thrive.
Just in case anybody is asking, have I left feral populations behind in the buildings I once kept reptiles? I do not think so but their food supply was a different matter: crickets, locusts and fruitflies and flour beetles were some of the escapees. In the one building still standing, the crickets may still be there.
Da Silva S-M, Maka A, Hartman T, Valero KW, Gilbert E. 2024. Two established introduced populations of the synanthropic gecko Hemidactylus turcicus (Linnaeus, 1758) in England. Herpetology Notes 17, 407-410
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