Conservation status of the St Paul's Island wall lizard (Podarcis filfolensis kieselbachi)

Abstract

The population of the endemic Maltese wall lizard, Podarcis filfolensis, on the small island of Selmunett (10.9 ha), off the northeast coast of the island of Malta, has been described as a distinct subspecies P .f. kieselbachi. Selmunett is a protected site and its lizard is a protected species. Reports of a pronounced decline in the Selmunett lizard population were investigated by systematic visual estimates of lizard population density started in 1999. Since August 1999, population counts declined from a high of 18 individuals observed per hour to zero by August 2005. The rate of decline was greatest for juveniles and females. Numerous cases of predation of the lizards by rats were observed and such predation seemed to be the cause of the decline in lizard population; visual counts of daytime-active rats, also started in 1999, showed a large rat population on Selmunett. In turn, the rat population appeared to have increased as a result of organic waste left by human visitors to the islet. A rat eradication programme implemented in 2006–2007 exterminated rats from Selmunett by the summer of 2007, when a few lizards captured in 2004 and kept in captivity since were released back on the islet to augment what remained of the population there (some lizards were spotted by casual observers, even if none were recorded during the actual counts). It remains to be seen if this attempt at saving the Selmunett wall-lizard population has been successful.