Elephant rewilding indirectly affects the abundance of an arboreal but not generalist savanna lizard

Abstract

Trophic rewilding provides a nature-based solution for biological conservation; however, empirical studies demonstrating rewilding effects are limited. Megaherbivores moderate the type and quality of habitat available to other fauna. However, these effects may take time to develop. Further, fauna responses to megaherbivore rewilding will depend on a suite of life-history traits and strategies that allow persistence within megaherbivore modified landscapes. We conducted a space-for-time field survey in South African savanna to determine if habitat modifications mediated by a reintroduced megaherbivore, the African savanna elephant (Loxodonta africana), impacts the abundance of the diurnal arboreal cape dwarf gecko (Lygodactylus capensis) and two generalist diurnal skinks [the variable skink (Trachylepis varia) and striped skink (Trachylepis striata), collectively] across a 47-year period. The relative abundance of lizards and six habitat attributes utilized by lizards were assessed at 30 sites stratified across three biophysically and climatically similar nature reserves with different elephant reintroduction times (no elephants, 2003, 1972). The arboreal gecko was less common at the reserve with an older reintroduction time than the other reserves and was most commonly observed on, and positively correlated with, the density of the corkwood tree (Commiphora mollis). The generalist skinks were common across all reserves and were observed in a variety of habitats. Our results suggest that elephant rewilding differently impacts lizard species with different life-history strategies and that these effects take prolonged periods to develop. Given such knowledge, a long-term understanding of post-rewilding interactions will be a key point when designing and assessing the success of rewilding initiatives.