Squamate scavenging services: Heath goannas (Varanus rosenbergi) support carcass removal and may suppress agriculturally damaging blowflies

Abstract

AbstractHuman‐induced environmental change has caused widespread loss of species that support important functions for ecosystems and society. For example, vertebrate scavengers contribute to the functional health of ecosystems and provide services to agricultural landscapes by removing carcasses and associated pests. Widespread extirpation of native Australian mammals since the arrival of Europeans in Australia has removed many scavenging species from landscapes, while scavenging mammals such as European red foxes (Vulpes vulpes) have been introduced. In much of Australia, squamate reptiles are the largest native terrestrial scavengers remaining, where large native mammals are extinct and conservation management is being undertaken to remove invasive mammals. The contribution of reptiles to scavenging functions is not well understood. In this study, we investigated the ecosystem functions provided by large reptiles as scavengers to better understand how populations can be managed to support ecosystem services. We investigated the ecosystem services provided by vertebrate scavengers in Australian coastal mallee ecosystems, focusing on the heath goanna (Varanus rosenbergi), the only extant native terrestrial scavenger in the region. We carried out exclosure experiments, isolating the scavenging activity of different taxonomic groups to quantify the contribution of different taxa to scavenging services, specifically the removal of rat carcasses, and its impact on the occurrence of agriculturally damaging blowflies. We compared areas with different native and invasive scavenger communities to investigate the impact of invasive species removal and native species abundance on scavenging services. Our results indicated that vertebrate scavenging significantly contributes to carcass removal and limitation of necrophagous fly breeding in carcasses and that levels of removal are higher in areas associated with high densities of heath goannas and low densities of invasive mammals. Therefore, augmentation of heath goanna populations represents a promising management strategy to restore and maximize scavenging ecosystem services.