Scavenging Ecology in the Australian Alps

Abstract

Scavenging is the consumption of carrion by living organisms. Often overlooked, it is common in all ecosystems. The assemblage of scavengers that act on carrion are important in maintaining this ecosystem service and are part of the necrobiome. Scavengers can be classified into distinct guilds comprised of vertebrates, invertebrates, and microorganisms whose collaborative roles operate efficiently when their community structure is diverse and intact. The goal of this thesis is to quantify how scavenger guilds can influence decay rates and how insect scavengers respond to the absence of competition from vertebrate scavengers. Individually, the functional roles vertebrate and insect scavengers are known, but there is limited understanding about how their interactions influence decay rates. Changes in the composition of vertebrate and insect scavenger communities around carrion may prolong carcass persistence possibly altering the localised effects of nutrient flow and increase the chance of carcass borne disease spread. This is important in Kosciuszko National Park where land managers cull both large herbivores and facultative vertebrate scavengers possibly creating and influx of carrion and altering the functionality of the vertebrate scavenger guild. Using exclusion cages, this study was able to limit access from vertebrate and insect scavengers to compare decay rates of carrion in the presence and absence of each guild. In contrast to similar systems, utilisation of carcasses by vertebrates did little to influence decay rates. This was pronounced in autumn and winter when carcasses persisted the longest despite elevated vertebrate activity and reduced competition from insects and microbes. This shifts the function of carrion removal towards insects as vertebrates contribute little to decomposition leading to a reduction of resiliency of this process. How each guild interacted and operated in the other’s absence had profound effects on carcass persistence.