Geckos are a highly diverse group of reptiles, known for their unique adhesive toe pads that allow them to climb nearly any surface. With over 2,000 recognized species, geckos are found across every continent except Antarctica, thriving in warm climates from dense jungles to arid deserts. While many species are common and widespread, a significant number of geckos are severely threatened with extinction, often depending on their geographic isolation and specialized habitat needs.
Defining Conservation Status
The international framework used to classify a species’ extinction risk is the IUCN Red List of Threatened Species, managed by the International Union for Conservation of Nature. This system provides a standardized method for assessing the global conservation status of plants, animals, and fungi. Assessments are based on rigorous criteria, including the rate of population decline, the size of the remaining population, and the extent of the species’ geographic range.
The IUCN Red List uses categories to reflect varying degrees of threat. Species not meeting the criteria for threatened status are listed as Least Concern (LC) or Near Threatened (NT). The three categories that define a species as “threatened” are Vulnerable (VU), Endangered (EN), and Critically Endangered (CR), representing high, very high, and extremely high risk of extinction in the wild. If there is insufficient information, a species is classified as Data Deficient (DD), and those with no individuals remaining in the wild are listed as Extinct in the Wild (EW).
The Global Conservation Status of Geckos
The conservation status of the family Gekkonidae is highly variable due to its immense species diversity. Approximately 654 species are categorized as Least Concern, suggesting they maintain widespread and stable populations, such as the common house geckos of the genus Hemidactylus. However, 218 species face significant threats, listed in the Vulnerable, Endangered, or Critically Endangered categories.
This risk is disproportionately concentrated in species with small, isolated ranges, particularly those endemic to islands. Island species are exceptionally vulnerable to localized threats when their habitats are destroyed. For example, the Manapany Day Gecko (Phelsuma inexpectata), endemic to a tiny area on Réunion Island, is listed as Critically Endangered due to its severely fragmented population.
The day geckos of the genus Phelsuma and the bent-toed geckos of the genus Cyrtodactylus contain a large number of threatened species. The Antanosy Day Gecko (Phelsuma antanosy) is Critically Endangered, restricted to a fragmented area of less than 10 square kilometers in Madagascar. Similarly, the Gia Lai bent-toed gecko (Cyrtodactylus gialaiensis) in Vietnam is Critically Endangered, restricted to a minuscule range under constant pressure from habitat conversion.
Primary Drivers of Population Decline
Habitat loss and fragmentation represent the foremost threat to gecko populations globally, especially for species with restricted ranges. Clearing forests for agriculture, mining, or urban development eliminates the specialized microclimates and resources these animals rely on. When habitat is broken into smaller patches, it isolates populations, making them less resilient to localized disasters and reducing genetic diversity.
Unsustainable collection for the international exotic pet trade is another significant driver of population decline. Visually striking species, such as many day geckos, are often collected from the wild, pushing already small populations toward collapse. For instance, the Tokay Gecko (Gekko gecko), while widespread, has seen massive population declines in parts of its native range due to demand for the pet trade and traditional medicine.
The introduction of non-native species to fragile ecosystems causes significant problems for native geckos. Invasive predators, such as rats, cats, and the brown tree snake (Boiga irregularis), have decimated native gecko populations on islands like Guam. Invasive competitor geckos, like the Giant Day Gecko (Phelsuma grandis), can displace or outcompete smaller native species, leading to local extinctions.
Climate change presents a growing threat, particularly for geckos that exhibit temperature-dependent sex determination (TSD). In TSD species, the incubation temperature dictates the sex of the hatchling. Warmer temperatures can lead to a skewed sex ratio, such as an overproduction of females, which compromises the reproductive potential of the population. Sustained increases in average temperature can severely limit the number of male offspring produced, ultimately causing a demographic collapse.