Excluding livestock from farm dams enhances native biodiversity

Amid a global biodiversity crisis and with over 50 % of the world's land dedicated to agriculture, solutions that enhance the biodiversity value of farmland are crucial. Fencing farm dams to prevent livestock access may provide numerous production and biodiversity benefits. However, we have limited information on the responses to fencing dams by various taxa, and its subsequent effect on community assemblages and ecosystem function. We investigated the impact of fencing farm dams on species richness, functional diversity, and community structure in a control-impact study in south-eastern Australia by comparing 20 fenced and 20 unfenced dams (40 dams total). We used a combination of in-person surveys, trail cameras, eDNA, and acoustic loggers to detect a wide range of fauna. We found significant differences in overall species richness, functional diversity and species composition between fenced and unfenced dams. Taxonomic groups including birds and mammals, and feeding guilds including carnivores and frugivores were more prevalent at dams that excluded livestock. Our results suggest that excluding livestock from farm dams preferentially benefits native species. At the species level, larger-bodied waterbirds such as dabbling ducks tended to prefer unfenced dams, while smaller woodland birds characteristic of nearby remnant woody native vegetation preferred fenced dams. We show that excluding livestock from farm dams has significant positive effects on biodiversity, ecosystem function and community structure. • Macrofauna were monitored at farm dams using multiple survey methods. • Fenced dams increased overall species richness, and functional diversity. • Native species, frugivores, and predators were also more prevalent in fenced dams. • Fenced dams supported more birds, and birds typical of remnant native vegetation. • Fencing farm dams may benefit both agricultural productivity and biodiversity.