Abstract: Abstract Conservation agencies within the European Union promote the restoration of traditional land uses as a cost-effective way to preserve biodiversity outside reserves. Although the European Union pursues the integration of the environment into strategic decision-making, it also dictates sectoral policies that may damage farmland biodiversity. We illustrate this point by outlining the socioeconomic factors that allow the persistence of traditional free-ranging horse husbandry in Galicia, northwestern Spain. Free-ranging Galician mountain ponies provide ecological and socioeconomic services including the prevention of forest fires, the maintenance of heathlands and wolves, and the attenuation of wolf-human conflicts. This traditional livestock system may have persisted because it entails negligible costs for farmers. Wolf predation upon Galician mountain ponies does not threaten farmer's economies and seems to be tolerated better than attacks to more valuable stock. Recently, European Union's regulations on animal welfare, carcass management, or meat production put new economic and administrative burdens on farmers, make free-ranging horse rearing economically unsustainable, and incentivize its abandonment. The aim of the European Union to integrate environmental policies may be successful to preserve farmland biodiversity only through careful anticipation of the side effects of apparently unrelated regulations on the fragile equilibrium that sustain traditional land uses.

Abstract: ABSTRACT For many ecosystems, feral horses are increasingly becoming an important if not dominant component of ungulate biomass and hence influence on community dynamics. Yet we still know little of how horses contribute to key ecological interactions including predator-prey and indirect competitive relationships at a community level. Notably, feral species like horses can exhibit life-history traits that differ from that of native (mainly artiodactyl) herbivore competitors. Artificial selection for traits like increased, early, or extended reproduction that have yet to be reversed by natural selection, coupled with naturally selected differences in anatomy and behavior, in addition to unique management objectives for horses compared to other species, means that the dynamics of feral horse populations are not likely to align with what might be expected of other large herbivores. Unexpected population dynamics and inherent biological asymmetries between native ungulates and feral horses may therefore influence the former via direct competition for shared resources and through enemy-mediated interactions like apparent competition. In several localities feral horses now co-exist with multiple native prey species, some of which are in decline or are species at risk. Compounding risks to native species from direct or indirect competitive exclusion by horses is the unique nature and socio-political context of feral horse management, which tends towards allowing horse populations to be limited largely by natural, density-dependent factors. We summarize the inherent asymmetries between feral horse biology and that of other ungulate prey species with consequences for conservation, focusing on predator-prey and emerging indirect interactions in multi-prey systems, and highlight future directions to address key knowledge gaps in our understanding of how feral horses may now be contributing to the (re)structuring of food webs. Observations of patterns of rapid growth and decline, and associated skews in sex ratios of feral horse populations, indicate a heightened potential for indirect interactions among large ungulate prey species, where there is a prevalence of feral horses as preferred prey, particularly where native prey are declining. In places like western North America, we expect predator-prey interactions involving feral horses to become an increasingly important factor in the conservation of wildlife. This applies not only to economically or culturally important game species but also at-risk species, both predators (e.g., wolves [Canis lupus], grizzly bears [Ursus arctos]) and prey (e.g., woodland caribou [Rangifer tarandus caribou]), necessitating an ecological understanding of the role of horses in natural environments that goes beyond that of population control. ? 2021 The Wildlife Society.