The impact of feral horses on grassland bird communities in Argentina

Abstract

The impact of introduced herbivores on the composition and structure of plant communities has been widely studied. However, little is known about how they affect wildlife. We studied the impact of feral horses under different grazing regimes on the communities of birds in a nature reserve in the Pampas grasslands in Argentina. The areas that had predominantly tall grass (enclosures and areas of moderate grazing intensity) showed the greatest species richness and total abundance of birds. Some species, e.g. the southern lapwing (Vanellus chilensis), were associated with the presence of horses, while others, e.g. pipits (Anthus spp), were more common in lesser grazed areas. The presence of feral horses was associated with an increase in the rate of predation of eggs which varied from 12.5% within the enclosures to 70% in grazed areas. It is suggested that the increase in predation rate was due to the increased visibility of the nests and an increase in the density of opportunist carnivores. Small areas of grassland in a good state of conservation could serve as sources that would maintain communities of birds in the more transformed sections.

Effects of Recreational Traffic on Alpine Plant Communities in the Northern Canadian Rockies

“…Taller vegetation may increase the habitat quality for some ground-nesting birds by decreasing the exposure of nests to predators and the risk of nests being trampled by pack animals as found in other regions (Zalba and Cozzani, 2004;Roodbergen et al, 2012). The increase in above-ground biomass and grass cover can increase food availability for guanacos.…”

Effects of feral free‐roaming horses on semi‐arid rangeland ecosystems: an example from the sagebrush steppe

“…Similarly, feral horses have been reported to negatively impact native wildlife in Argentina (Zalba and Cozzani 2004). Our research suggests that feral horse grazing is limiting the recruitment of sagebrush which likely prolongs the time that the plant community is unsuitable habitat for sagebrush associated wildlife species.…”

Multi-year fertility reduction in free-roaming feral horses with single-injection immunocontraceptive formulations

“…In the USA, feral horses are federally managed and protected under the Free-Roaming Wild Horse and Burro Protection Act of 1971 and continue to overpopulate rangelands where they can negatively impact grasslands, riparian areas, soils and other wildlife 4 species (Rogers 1990;Beever and Brussard 2000;Levin et al 2002;Beever and Brussard 2004;Zalba and Cozzani 2004;Beever and Herrick 2006). Despite this trend, lethal control is largely unacceptable to the public.…”