Many large carnivores facilitate the acquisition of carrion for scavengers and decomposers, ,, but large carnivores and other dominant scavengers also compete with and limit the consumption of carrion by smaller species, , –. Competition, one of the most important processes in evolution and ecology, among facultative scavenger species is therefore likely to be an important factor in the acquisition of carrion, with the potential to influence community assemblages at larger scales,. However, ungulate carcasses are also patchily distributed and only available for short periods of time. Ĭarcasses of large bodied ungulate species are a particularly rich source of nutrition, especially during lean seasons such as late winter in North America when many species, including carnivores, struggle to meet their energetic requirements,. Despite scavenging being a wide-spread and ecologically significant behaviour, our understanding of the biotic constraints that limit access to carrion for vertebrate scavengers is limited. This is at least partly due to the numerous vertebrate species which adopt scavenging to increase reproductive success and survival, and hence their individual fitness (e.g., – ). In fact, Wilson and Wolkovich reported that in many food webs, a greater amount of energy is transferred through scavenging of carrion than through direct predation. For example, by transferring energy across trophic levels, scavengers are thought to increase the stability of ecological communities and food webs. Both the direct and indirect effects of carrion, and the intense competition that occurs over these resources, are increasingly being recognized as important processes in structuring ecological communities –. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist.Ĭarrion is an essential but temporal resource for countless species ranging from microbes to vertebrates –. Allen was supported by a Victoria University of Wellington tuition scholarship. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: The University of California Davis, and the California Department of Fish and Wildlife generously provided financial support for the project. Received: MaAccepted: JPublished: July 10, 2014Ĭopyright: © 2014 Allen et al. PLoS ONE 9(7):Įditor: Brock Fenton, University of Western Ontario, Canada The interactions between large carnivores and scavengers should be considered in future studies of food webs and ecological communities.Ĭitation: Allen ML, Elbroch LM, Wilmers CC, Wittmer HU (2014) Trophic Facilitation or Limitation? Comparative Effects of Pumas and Black Bears on the Scavenger Community. Our results suggest that scavengers have species-specific adaptions to exploit carrion despite large carnivores, and that large carnivores influence the structure and composition of scavenger communities. In addition, we found that pumas and black bears both increased the nestedness (a higher level of order among species present) of the scavenger community. Black bears also had large negative effects on scavenger sum feeding times (88.5 min☑9.8 SE at carcasses where bears were present, 372.3 min±50.0 SE at carcasses where bears were absent). In contrast, black bears, as the dominant scavenger in the system, limited consumption of carrion by scavengers as evidenced by the observed reduction of scavenger species richness recorded at carcasses where they were present (mean = 2.33☐.28 SE), compared to where they were absent (mean = 3.28☐.23 SE). Pumas, as a top-level predator, facilitated the consumption of carrion by scavengers, despite significantly reducing their observed sum feeding times (165.7 min☒1.2 SE at puma kills 264.3 min☓0.1 SE at control carcasses). We found that pumas ( Puma concolor) and black bears ( Ursus americanus) had different effects on their ecological communities. We used an experimental approach based on motion-triggered video cameras at black-tailed deer ( Odocoileus hemionus columbianus) carcasses to measure the comparative influences of two large carnivores in the facilitation and limitation of carrion acquisition by scavengers. Large carnivores facilitate the movement of energy across trophic levels through the scavenging and decomposition of their killed prey, but competition with large carnivores is also likely to constrain acquisition of carrion by scavengers. Scavenging is a widespread behaviour and an important process influencing food webs and ecological communities.
0 Comments
Leave a Reply. |