Positive and negative unintended human-induced effects on Iberian mole abundance at the edge of its distribution area

Humans can unintentionally induce both positive and negative effects on wildlife presence and abundance, with organisms living in or associated with agricultural areas being good examples. Our study focused on a 1500. ha area (75 sampled 100. m × 50. m plots) at the driest edge of the endemic Iberian mole Talpa occidentalis distribution range, where the species is listed as "Vulnerable". Here, poplar cultivations dominate wasteland and other irrigated and non-irrigated crops. The poplar irrigation system was traditionally based on a network of straight ridges, although it is rapidly being replaced with a sophisticated procedure which permits water to spread with ridges no longer being needed. In these habitats, ridges are relevant for moles because they provide dry shelters for nests. In this paper we explore (a) mole local habitat preferences and (b) the impact of changes in poplar irrigation systems on mole abundance. Iberian mole abundance positively related to earthworm biomass and numbers; however, multivariate analyses highlighted the effect of herbaceous cover (positive relationship), rocks cover and soil hardness (negative relationship), and habitat type (poplar being the preferred one). Furthermore, mole abundance was substantially higher in poplar groves where ridges were still present than where they were not. We conclude that Iberian moles in semi-arid environments are favoured by poplar plantations but, at the same time, they are highly vulnerable to recent changes in traditional agriculture practices. Therefore, this study shows how agricultural habitats can benefit some species of conservation concern, especially some temperate species at the edge of their range or in extreme ecological conditions. Changes in agricultural practices that negatively affect the suitability of such habitats can compromise these species's conservation, as we found for the Iberian mole. © 2012 Deutsche Gesellschaft für Säugetierkunde.