Abstract

We summarize what is known of reptilian extinctions worldwide over the last 10,000 years. Two patterns are evident: the great majority of these extinctions have occurred on islands, and they are usually due to human-related disturbance. The effects of human-related disturbance are calibrated by measuring the rate of extinction for two sets of Holocene landbridge islands where human impact has been minimal. Extinction rates for islands with a history of human habitation are also determined for comparison. The results of this investigation indicate that human-related disturbance increases extinction rates by roughly an order of magnitude for smaller islands. Interestingly, very large islands and continental areas exhibit lower rates of extinction than predicted from the landbridge island data. More detailed consideration of the cause of species extinction in particular cases strongly implicates introduced predators, chiefly mongoose, rats, cats, and dogs as the agents of many human-related extinctions, whereas competition with introduced reptiles appears to have had little impact on native species.