Amphibia-Reptilia 34 (2013): 233-239 Rapid enigmatic decline drives the fire salamander (Salamandra salamandra) to the edge of extinction in the Netherlands Annemarieke Spitzen-van der Sluijs 1,4,∗ , Frank Spikmans 1 , Wilbert Bosman 1 , Marnix de Zeeuw 2 , Tom van der Meij 2 , Edo Goverse 1 , Marja Kik 3 , Frank Pasmans 4 , An Martel 4 Abstract. In the Netherlands, the fire salamander (Salamandra salamandra) is at the edge of its geographic range and is restricted to three small populations in the extreme south of the country. Despite the species being listed as ‘Endangered’ on the national Red List, the situation was considered to be stable. However, from 2008 onwards dead individuals were seen on more than one occasion. A sharp decline in numbers has been observed since 2010 (96%; P< 0.01), but we were unable to attribute this to any known cause of amphibian decline, such as chytridiomycosis, ranavirus or habitat degradation. The present work describes this enigmatic decline, and we discuss these results in the context of possible causes. Keywords: enigmatic decline, local extinction, mortality, Salamandra salamandra, terrestrial salamanders. Introduction Amphibians are experiencing declines globally, exemplified not only by population declines, but also by range reductions and extinctions of some species (Houlahan et al., 2000; Stuart et al., 2004; IUCN, 2012), and they may be part of a sixth major extinction event (Wake and Vredenburg, 2008), for which there is no single cause (Blaustein et al., 2011; Hof et al., 2011). In the Netherlands, despite 50% of the am- phibian species being on the Red List (Van Delft, Creemers and Spitzen-van der Sluijs, 2007), there were, until quite recently, no indications of an acute decline that could result in the extinction of a species from the country. Even when the two major in- fectious drivers of amphibian declines were present, Batrachochytrium dendrobatidis and 1 - Reptile, Amphibian and Fish Conservation the Nether- lands, P.O. Box 1413, 6501 BK Nijmegen, The Nether- lands 2 - Statistics Netherlands, P.O. Box 24500, 2490 HA Den Haag, The Netherlands 3 - Dutch Wildlife Health Centre, Utrecht University, P.O. Box 80158, 3508 TD Utrecht, The Netherlands 4 - Department of Pathology, Bacteriology and Avian Dis- eases, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium ∗ Corresponding author; e-mail: a.spitzen@ravon.nl ranavirus (Daszak, Cunningham and Hyatt, 2003; Spitzen-van der Sluijs et al., 2010; Kik et al., 2011) no specific decline has been observed. However, the sudden, steep decline of the fire salamander (Salamandra salamandra ter- restris) in the Netherlands is a new phe- nomenon. In the Netherlands, fire salamanders live at the very edge of their distribution and are confined to the old growth stages of de- ciduous forests on hillsides. Surface activity is limited to humid periods with night tempera- tures above 5°C. Mating usually occurs in au- tumn, the larvae are deposited from late winter until spring. In the Dutch populations, the ani- mals mature at an age of 6 years in both males and females. Specimens can live for 20 years in this region (Gubbels, 2009). Listed as ‘En- dangered’ on the national Red List, the species’ range has decreased by 57% since 1950. This is probably due to the drying up of streams, or their canalisation and intensive cleaning. Addi- tional threats are collection for the pet trade and the use of herbicides in surrounding agricultural land (Van Delft, Creemers and Spitzen-van der Sluijs, 2007; Gubbels, 2009). Currently, the species is only known from two native populations and another small, in- troduced, non-native population, all three in the extreme south of the Netherlands. The © Koninklijke Brill NV, Leiden, 2013. DOI:10.1163/15685381-00002891