Flooding, season and habitat interact to drive changes in vertebrate scavenging and carcass persistence rates

Abstract

Scavenging dynamics are influenced by many abiotic and biotic factors, but there is little knowledge of how scavengers respond to extreme weather events. As carrion is a major driver of the organisation and structure of food webs within ecological communities, understanding the response of scavengers to extreme weather events is critical in a world that is increasingly subject to climate change. In this study, vertebrate scavenging and carcass persistence rates were quantified in the Simpson Desert of central Australia; a system that experiences major fluctuations and extremes in weather conditions. Specifically, a total of 80 adult red kangaroo (Osphranter rufus) carcasses were placed on the landscape and monitored using remote sensor cameras. This included 40 carcasses monitored before and then 40 carcasses monitored after a major flooding event. The carcasses were monitored equally before and after the flood across different seasons (warm and cool) and in dune and interdune habitats. Overall, a total of 8124 scavenging events for 97,976 visitation minutes were recorded for 11 vertebrate species within 30 days of carcass placement pre- and post-flood. Vertebrate scavenging increased post-flood in the warm season, especially by corvids which quadrupled their scavenging events during this time. There was little difference in carcass persistence between habitats, but carcasses persisted 5.3-fold longer post-flood in warm seasons despite increased vertebrate scavenging. The results demonstrate that a flood event can influence scavenging dynamics and suggest a need to further understand how seasons, habitats and extreme weather events can drive changes in carrion-based food webs.