Short Communication A paradox of restoration: prey habitat engineering for an introduced, threatened carnivore can support native biodiversity L IINA R EMM ,A SKO L ÕHMUS and T IIT M ARAN Abstract Conservation of charismatic vertebrates in mod- ern landscapes often includes habitat engineering, which is well supported by the public but lacks a consideration of wider conservation consequences. We analysed a pond management project for an introduced island population of captive-bred, Critically Endangered European mink Mustela lutreola. Ponds were excavated near watercourses in hydrologically impoverished forests to support the main prey of the mink (brown frogs Rana temporaria and Rana arvalis). A comparison of these ponds with other, nat- ural, water bodies revealed that the (re)constructed ponds could reduce food shortages for the mink. Moreover, the ponds provided habitat for macroinvertebrates that were uncommon in the managed forests in the study area, includ- ing some species of conservation concern. The cost- effectiveness of the management of charismatic species can be increased by explicitly including wider conservation targets at both the planning and assessment stages. Keywords Amphibians, Estonia, focal species, habitat deg- radation, macroinvertebrates, Mustela lutreola, Odonata, pond management This paper contains supplementary material that can be found online at http://journals.cambridge.org H abitat management for charismatic threatened species is a common conservation activity, and it is important to understand the contribution this makes to wider bio- diversity conservation at the scale of species and ecosystems. In addition, the consequences of species-oriented habitat management can inform debates on the efficacy of surrogate species (Caro, ) and realistic goal-setting in restoration ecology. The concept of surrogate species was linked expli- citly with habitat management for threatened species by Lambeck (), who suggested that the conservation or reconstruction of habitats be based on a suite of focal species sensitive to each threat. Hobbs et al. () suggested that traditional habitat restoration needs to be replaced by an approach that maintains ecosystem services in human-impacted environments by means of various inter- ventions. Thus, if sustaining a threatened species is desirable either for its surrogate or public-perceived values, it may be acceptable to engineer critical characteristics of its degraded habitat beyond the natural range of variability. It is less clear, however, to what extent such practices support the wider aims of biodiversity conservation. Here we explore a situation in which management for a threatened flagship species has gone beyond conventional habitat restoration. The target species, the European mink Mustela lutreola, is a Critically Endangered mustelid threat- ened by habitat loss and the impact of the alien American mink Neovison vison (Maran et al., ). Balancing these threats, the Foundation Lutreola and Tallinn Zoo estab- lished a mink population in , using captive-bred indi- viduals, on the remote Estonian island of Hiiumaa ( km  , % forest cover; Fig. ). The island has no historical records of this species but the abundance of farm-escaped American mink (now eradicated and the farm closed), combined with field assessments of riparian areas, suggested a potential car- rying capacity for – European mink (Macdonald et al., ; Maran & Põdra, ). The main limiting factor is the sparse network of natural streams and a severe reduction of lakes and pools as a result of artificial drainage and lowering of the water level for forestry and agriculture (Veering, ). Riparian areas are the main habitat of the European mink, which normally stays within  m of streams (Danilov & Tumanov, ). Although larger ditches could provide alternative habitat, drainage has presumably reduced the mink’s prey base, notably the brown frogs Rana temporaria and Rana arvalis (Suislepp et al., ; Põdra et al., ). Improving the prey base via large-scale hydro- logical restoration would have been complicated, and artifi- cial ponds were therefore constructed. Here, we explore whether these artificial ponds supported not only the mink’s prey but also other native macroinvertebrates. Twenty-three small (–, m  ) ponds were con- structed or reconstructed in forests and meadows. The ponds were c.  m deep, to provide an environment suitable for amphibian tadpoles up to the completion of LIINA REMM (Corresponding author) and ASKO LÕHMUS Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise Street 46, EE-51014 Tartu, Estonia. E-mail liina.remm@ut.ee TIIT MARAN Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia, and Species Conservation Lab, Tallinn Zoological Gardens, Estonia Received  January . Revision requested  February . Accepted  March . First published online  September . Oryx, 2015, 49(3), 559–562 © 2014 Fauna & Flora International doi:10.1017/S0030605314000271 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605314000271 Downloaded from https://www.cambridge.org/core. IP address: 54.161.69.107, on 31 May 2020 at 01:44:08, subject to the Cambridge Core terms of use, available at