Exotic scavengers replace native ones outside a protected area in Madagascar

Abstract

Madagascar rainforests exhibit very high levels of biodiversity and endemicity but face numerous impacts that jeopardize their biological communities. Some ecological processes are deeply understudied in these ecosystems, such as scavenging (i.e., consumption of decaying meat) on an island lacking obligate scavengers. This work addressed the effect that habitat type, carcass type and land protection have on the scavenger community in Madagascar. For this approach, thirty small carcasses (~50 g) were installed in areas of primary and secondary forest within and around Ranomafana National Park and were monitored using photo-trapping techniques over 24 h. The cameras detected three endemic species, the Malagasy civet (Fossa fossana), the ring-tailed vontsira (Galidia elegans) and, for the first time, the tufted-tailed rat (Eliurus sp.), and two introduced species, the cat (Felis catus) and the black rat (Rattus rattus) making trophic use of carcasses. Habitat composition and land protection influenced the presence of native and exotic species within the scavenger community, but not species richness, abundance or carcass detection time. All species detected in primary forest were native and endemic, whereas to only 57 % of those detected in secondary forest. We only registered invasive species outside the protected area, while native, endemic species were restricted within the park borders. Habitat protection and anthropization may play a key role in the presence of invasive species in the community of scavenger vertebrates in Madagascar.