The Mediterranean house gecko, Hemidactylus turcicus, is a small lizard typically measuring 4 to 5 inches in length. Its body can appear gray, brown, or tan, often with pink or purple undertones and a bumpy texture. These geckos are primarily nocturnal, becoming most active around dusk. This widespread reptile often prompts questions about its ecological role and whether it is considered an invasive species in regions outside its native range.
Understanding Invasive Species
An invasive species is defined as an organism that is not native to a particular ecosystem and causes, or is likely to cause, economic harm, environmental harm, or harm to human health. Not all non-native species are considered invasive; many are introduced without significant disruption. A species becomes invasive when its introduction results in a measurable detrimental effect on native biodiversity, ecosystem functions, or human interests. Such impacts can include outcompeting native organisms for resources, altering habitats, or introducing diseases.
The Mediterranean House Gecko’s Spread and Characteristics
The Mediterranean house gecko is native to the Mediterranean region, encompassing areas like southern Europe, North Africa, and parts of the Middle East. Its widespread global presence is largely a result of human-assisted transport, often inadvertently as “hitchhikers” on cargo, plants, or building materials. Since its first documented appearance in Florida in 1915, this gecko has expanded its range across various parts of the world, including the Southern and Southeastern United States, the Caribbean, and parts of South America.
Several characteristics contribute to the gecko’s success as a colonizer in new environments. They are highly adaptable, thriving in diverse habitats from rocky cliffs to urban structures, often utilizing human dwellings for shelter and foraging. Their rapid reproductive rate, with females laying multiple clutches of one to two eggs from April to August, aids population growth. As generalist insectivores, they consume a wide variety of insects, spiders, and other arthropods, exploiting available food sources in new locations.
Impacts on Local Ecosystems
The presence of Mediterranean house geckos in non-native environments raises questions about their ecological impacts. While often considered minor compared to other invasive species, they can potentially compete with native insectivorous reptiles for food resources like moths, beetles, and spiders. This competition is primarily for nocturnal insect prey.
Their consumption of local insect populations could alter insect community structures, although specific large-scale impacts are not broadly documented. The extent of their disruption appears limited, especially in highly urbanized areas where native insectivores may already be scarce. However, in more sensitive or isolated ecosystems, such as islands, even seemingly small competitive advantages could lead to localized declines in native species.
Managing Their Presence
For homeowners encountering Mediterranean house geckos, coexistence is generally the most practical approach due to their widespread nature and typically minor impact. These geckos are not venomous and rarely bite humans, posing no direct threat. Many people even view them as beneficial due to their consumption of common household pests like roaches and moths.
To deter them from entering homes, measures include sealing cracks and openings around windows, doors, and foundations. Reducing outdoor lighting at night can also help, as these lights attract the insects that geckos feed upon. Large-scale eradication efforts are generally not undertaken for this species given their broad distribution and relatively low ecological impact compared to other invasive organisms. However, localized control might be considered in specific sensitive habitats where their presence could pose a greater risk to vulnerable native species.