Ecological roles and conservation challenges of social, burrowing, herbivorous mammals in the world’s grasslands

© The Ecological Society of America www.frontiersinecology.org G ecosystems worldwide are fundamentally shaped by an underappreciated but key functional group of social, semi-fossorial (adapted to burrowing and living underground), herbivorous mammals (hereafter, burrowing mammals). Examples include not only the phylogenetically similar species of prairie dogs of North America (Cynomys spp); ground squirrels (Family Sciuridae) of North America, Eurasia, and Africa; and marmots (Marmota spp) of North America and Eurasia, but also the more distantly related but functionally similar plains vizcachas (Lagostomus maximus), Patagonian maras (Dolichotis patagonum), and degus (Octodon degus) of South America; pikas (Ochotona spp) of Asia; ice rats (Otomys sloggetti) and springhares (Pedetes capensis) of Africa; and burrowing bettongs (Bettongia lesueur) and southern hairy-nosed wombats (Lasiorhinus latifrons) of Australia (Figure 1). Often living in colonies ranging from tens to thousands of individuals, these mammals collectively transform grassland landscapes through their burrowing and feeding activity. By grouping together socially, they also create distinctive habitat patches that serve as areas of concentrated prey for many predators. Their ecosystem engineering and trophic effects help maintain grassland biodiversity and, consequently, they frequently play keystone roles in these ecosystems (Figure 2). Despite their importance to grassland ecosystems, burrowing mammal populations have declined dramatically, primarily as a result of human impacts; indeed, because grasslands provide the world’s most important habitat for agricultural and livestock production, burrowing mammals are often in direct conflict with human activities (Smith et al. 2006; Miller et al. 2007; Delibes-Mateos et al. 2011). Human-mediated introductions of exotic species, disease agents, and overhunting are also reducing their populations (Branch et al. 2002; Gage and Kosoy 2005; Wingard and Zahler 2006; Rodriguez 2009). The population dynamics and ecological roles of most burrowing mammal species remain poorly understood, however. The patterns discussed here apply to most, but not necessarily all, of the species mentioned. What is known about the few well-studied species suggests that burrowing mammals likely play widespread and important ecological roles, and that their loss can have cascading detrimental effects on the grassland ecosystems on which both humans and wildlife depend. An important challenge facing grassland managers is maintaining the important functional roles of these burrowing mammals in ways that are compatible with human activities. Here, we present a conceptual model (Figure 2) that illustrates the common but underappreciated roles REVIEWS REVIEWS REVIEWS