Rocky outcrops: A hard road in the conservation of critical habitats

Rocky outcrops are geological features that encompass a wide variety of physical environments, including escarpments, overhangs, cliffs, tors, boulder-heaps and insular domes (inselbergs). They support high levels of species diversity and endemism, and provide stable micro-climates for thousands of years. They provide critical breeding sites for many top order mammalian and avian predators; nesting sites for colonial species such as seabirds, bats and swifts and ecological refuges for ancient lineages. Rock overhangs and caves also provide important insights into our ecological past where they contain the remains of extinct species. Because rocky environments are generally less fertile, steep-sided and less accessible than the surrounding landscape, they are typically less prone to human disturbances. Nonetheless, many rocky outcrops, particularly in commodity production landscapes, face a variety of threats including soil compaction and erosion caused by livestock; nutrient enrichment and weed invasion; introduced predators; and physical damage caused by recreational and quarrying activities. Even rocky outcrops in seemingly pristine environments may be affected by altered fire regimes, air pollution (including acid rain) and potentially climate change. In agricultural landscapes, various approaches have been taken to conserve rocky outcrops, including land acquisition for conservation, fencing from livestock and private land conservation agreements with landholders. In more intact landscapes, targeted actions to conserve rock-dwelling fauna include limiting human access to critical breeding sites, baiting to reduce pressure from introduced predators, restoring rock microhabitat and translocation of endangered species. Future management actions will need to involve better inventory of the biophysical attributes and fine-scale mapping to improve the awareness of these small natural features.