Using artificial rocks to restore nonrenewable shelter sites in human-degraded systems

Many animals spend much of their time within retreat sites underneath loose surface rocks and may be highly selective in terms of the physical characteristics of the sites that they use. If such shelters are eliminated by anthropogenic activities, such as rock removal for landscaping, the only way to restore these nonrenewable habitats may be to replace them with artificial rocks. To construct artificial rock habitats, we need to understand which rock attributes are important for faunal use and develop methods to mimic these important natural retreat site characteristics. Based on our prior understanding of rocky retreat sites used by reptiles in sandstone outcrops of southeastern Australia, we constructed realistic-looking artificial rocks from fiber-reinforced cement and evaluated (1) the degree to which they mimicked natural retreat sites in both thermal regime and three-dimensional crevice structure and (2) their colonization by fauna after deployment in the field. Our results demonstrate that thermal regimes and crevice structures beneath the artificial rocks were similar to those beneath natural rocks. In addition, 100% of the artificial rocks were colonized (by 45 invertebrate, six lizard, and two snake species, including the endangered Broad-headed snake, Hoplocephalus bungaroides) after only 40 weeks. Together, these results suggest that restoring degraded habitats for rock-dwelling species is feasible and can provide a rapid means of enhancing shelter-site availability for such species.