Animal Island reptiles disappear before they are even known
Countless fascinating reptile species live on remote islands. But despite their importance for nature, many of these unique animals are on the brink of extinction - even before science has been able to study them.
08.11.2025, 05:00
SDA
In the journal "Conservation Science and Practice", a research team led by the University of Oxford reports that island reptiles are particularly vulnerable because their isolated habitats make them extremely fragile.
Although islands make up less than seven percent of the Earth's surface, they are home to a large proportion of global biodiversity. Around a third of the approximately 12,000 known reptile species are found on islands, including species such as the Galapagos giant tortoise and the Komodo dragon. "Reptiles possess several physiological and behavioral traits - such as impermeable skin and the ability to survive long periods without food or water - that make them particularly good island dwellers," the study says.
What threats are reptiles exposed to?
The analysis shows that around 30 percent of reptiles on islands are threatened with extinction - the global average is 12 percent. Since 1960, only just under 7 percent of scientific studies on reptiles have dealt with endangered island species.
Populations are mainly threatened by agricultural expansion, deforestation, pollution and introduced species. Introduced cats on islands, for example, have dramatic consequences.
Hardly any defense mechanisms
This is because many island reptiles have evolved in the absence of mammalian enemies and therefore have no strong defense mechanisms, explained lead author Ricardo Rocha. "This makes them easy targets for introduced predators such as free-ranging cats, which are one of the main causes of extinction on islands."
At the same time, reptiles such as snakes, turtles and geckos are key species for island ecosystems. "On Madeira Island, for example - my birthplace - there are wall lizards everywhere, which hunt insects, pollinate plants and eat fruit." Research has shown that a single cat on the island can eat more than 90 lizards in just one year. "An impressive example of how introduced predators can unbalance fragile island ecosystems," said Rocha.
The example of the Príncipe emerald snake
The scientists analyzed research between 1960 and 2021 and found that larger and more widespread species received more attention, while smaller and newly discovered island species were largely ignored.
One example is the Príncipe emerald snake (Hapsidophrys principis), which only occurs on the small island of Príncipe in the Gulf of Guinea and was first described in 1906. This endemic snake species is a prime example of an island species that is highly endangered due to its isolation. Despite its ecological importance as a predator in this sensitive ecosystem, little research data is available on its lifestyle and population development.
The authors of the study, in which the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) was also involved, suggest more targeted research on island reptiles, especially those most at risk of extinction. Other recommended measures include the promotion of partnerships between national institutions and island communities and the integration of knowledge from non-academic sources.
