Recovering the Reptile Community after the Mine-Tailing Accident of Aznalco ´ llar (Southwestern Spain) Rocı´oMa ´ rquez-Ferrando, 1 Juan M. Pleguezuelos, 1,2 Xavier Santos, 3 Diego Ontiveros, 1 and Juan R. Ferna ´ ndez-Cardenete 1 Abstract Ecosystem restoration requires that habitat requirements of all species be considered. Among animal communities in Mediterranean ecosystems, reptiles, as ectothermic vertebrates, need refuges for avoidance of extreme en- vironmental temperatures, concealment from predators, and oviposition sites. In 1998, a massive amount of tail- ings broke out of the holding pond of the Aznalco ´ llar mine (southwestern Spain) and polluted the Guadiamar river valley. After the accident, a soil- and vegetation restoration program began, and the Guadiamar Green Corridor was created to connect two huge natural areas, Don ˜ ana National Park and the Sierra Morena. Within this corridor, the reptile community remained dramati- cally impoverished, probably because of elimination of all natural refuges during the soil restoration program. To test this hypothesis, we set an array of artificial re- fuges (logs) in a large experimental plot. During the 5 years of the experiment (2002–2006), the area managed with artificial refuges exhibited a better and faster re- covery of the reptile community in species richness and individual abundance than did the control area with no artificial refuges. Moreover, reptile colonization of the Guadiamar Green Corridor was transverse rather than lineal—that is, it did not act as a corridor for rep- tiles, at least in the first stages of colonization. This sug- gests that landscape restoration programs should not neglect refuge availability, a limiting resource for reptile species. Key words: artificial refuges, mine spill, recovering animal communities, reptiles, Spain. Introduction Restoration of degraded ecosystems is based on the assumption that rebuilding habitat will rehabilitate natural communities (Litt et al. 2001). Because of ecosystem com- plexity, however, even the most carefully designed habitat rebuilding programs rarely take the requirements of all natural communities into account. Programs for vegeta- tion restoration usually do not meet requisites for faunal recovery, although those focused on mammal and bird communities do not satisfy requirements for ectothermic vertebrates (Buffington et al. 2000; Wike et al. 2000; Martı´n & Lo ´ pez 2002; Nichols & Nichols 2003) and moni- toring success of restoration programs with respect to dif- ferent communities of organisms is essential (Palmer et al. 1997; White & Walker 1997; Block et al. 2001; Scott et al. 2001). Reptiles play an important role in ecosystems, serving as prey, predators, and seed dispersers (Schoener & Spiller 1996; Jones 2002). They require natural cover that offers protection against visually oriented predators or microclimatic conditions favoring thermoregulation and reproduction (i.e., nesting sites) that differs from that required by birds and mammals (Huey et al. 1989). Scar- city of shelter negatively affects reptiles at individual, pop- ulation, and community levels (Goode et al. 2005) and how habitat management will affect reptile communities can be tested in degraded ecosystem restoration programs. North of Don ˜ ana National Park, in southwestern Spain, a mine-tailing spill polluted a large area, giving rise to an interesting case study involving soil and vegetation resto- ration and recovery of the terrestrial reptile community in the contaminated area. On 25 April 1998, the wall of the holding pond for tailings of the Aznalco ´ llar mine col- lapsed and more than 6 million m 3 of toxic solids and acidic waters with high concentrations of arsenic and heavy metals (Zn, Pb, Cu, Sb, Tl, and Cd) were released into the Guadiamar floodplain. Waste waters spread to a width of 1,000 m in some areas along 62 km of the river (4,286 ha in area) and included the northern zone of Don ˜ ana Natural and National Parks (a Biosphere Reserve; Pain et al. 1998; Gallart et al. 1999; Montes 2002). From qualitative and quantitative standpoints, the largest environmental pollution accident recorded in 1 Departamento de Biologı ´a Animal, Universidad de Granada, E-18071 Granada, Spain 2 Address correspondence to J. M. Pleguezuelos, email juanple@ugr.es 3 Departamento de Biologia Animal (Vertebrats), Universitat de Barcelona, Avgda. Diagonal 645, E-08028 Barcelona, Spain Ó 2008 Society for Ecological Restoration International doi: 10.1111/j.1526-100X.2008.00404.x 660 Restoration Ecology Vol. 17, No. 5, pp. 660–667 RESEARCH ARTICLE SEPTEMBER 2009