Scavenging by vertebrates: Patterns of resource acquisition and implications for multi-trophic dynamics

Travis Lee DeVault, Purdue University

Abstract

I examined the fate of small mammal carrion in forested habitats of the southeastern USA and considered the implications of carrion use on ecological processes. First, I synthesized the available literature on scavenging by vertebrates in terrestrial ecosystems. My review suggested that carrion use by vertebrates is much more prevalent than conventional theory implies, and, rather than a curiosity of animal behavior, is a key ecological process. Although several factors have led to the relative lack of information concerning scavenging behavior in vertebrates, several lines of evidence suggest that vertebrates use carrion resources more extensively than has been widely assumed. I concluded that a deeper understanding of carrion use by facultative scavengers would improve our knowledge of community and ecosystem processes, especially the flow of energy through food webs. In empirical work, I used remote cameras to investigate the efficiency of vertebrate scavengers at the Savannah River Site, South Carolina. Rodent carcasses, differing in size and visual conspicuousness, were placed in upland pine forests and bottomland hardwood forests throughout the year. Twenty-one vertebrate species were photographed removing carcasses, although raccoons (Procyon lotor), opossums (Didelphis virginiana), feral pigs (Sus scrofa), and gray foxes (Urocyon cinereoargenteus) scavenged most frequently. The proportion of small carcasses scavenged by vertebrates, as opposed to those that decompose, appears to be influenced by carcass size and habitat type, but not visual conspicuousness. Olfactory cues are the dominant stimuli used by vertebrate scavengers in forested habitats to locate small carrion items. Further, my work suggested that ambient temperature was the prevailing factor mediating competition among scavengers and decomposers. During the summer, arthropods consumed most (∼80%) carcasses before vertebrates could detect and consume them. During cooler months, vertebrates scavenged upwards of 50% of the available carrion because of lower levels of arthropod activity. However, competitive relationships among scavengers and decomposers during cool weather are complex, and may vary considerably across years. I conclude that scavenging ecology clearly is a topic that is ripe for further investigation and rich with the potential to advance our understanding of critical ecological processes, especially the flow of energy through food webs.

Degree

Ph.D.

Advisors

Rhodes, Purdue University.

Subject Area

Forestry|Ecology

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