The problem is multifaceted. Habitat loss and degradation may be the largest single factor in reptile loss. For even when part of a habitat is protected, such as a wetland, the surrounding terrestrial habitat needed by semiaquatic reptiles often is not. Conservation biologists hold as a basic tenet of ecology that intact habitat is necessary for species persistence and well-being. But habitat destruction is just the beginning of the problem.
Invasive species introduced to new areas can spell real danger for reptiles.
One example is the Galapagos tortoise, now near extinct due largely to introduced rats which destroy the tortoise eggs. Other problems include environmental pollution, disease and even the simple presence of humans among a fragile population. The commercial use of reptiles is also cited as a cause for declines. The harvesting of reptiles for pets, food and for use in folk medicines can result in overcollection. This kind of use affects reptiles more than amphibians.