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. The EU commissioners have yet to respond to the activists' letter.Scavenging is a widespread behaviour and an important process influencing food webs and ecological communities. And even dead cows can be left in the traditional Spanish carcass dumps, just as in the past, without any problems, as long as the herd has not had any cases of BSE and the dead animals are younger than two years old. There has yet to be any reported case of BSE among horses, asses or mules, the activists say, meaning their carcasses can be left in pastures without risk. The activists said that the changes "would in no way jeopardize the population's safety from the epidemic." For this reason, the environmentalists from Euronatur and their Spanish colleagues from Fapas sent the results of their study to the EU officials responsible for such matters - Health Commissioner Markos Kyprianou and Environment Commissioner Stavros Dimas - in early December and demanded "urgent" amendments to Regulation 1774/2002. It appears that no one in Brussels has given the plight of the bears much thought. They can't get into the fenced-off bird feeding stations, and a 1,000-kilometer (621-mile) trip is out of the question. In this way, though, the vultures are at least expanding the habitat of the species and thereby reducing the demand for carcasses in their original territory.įor the bears, though, emigration is no solution. Flocks of the large scavengers, whose wingspan can reach 3 meters (9.8 feet), have been sighted in Germany, Belgium and France.īut even this long trip doesn't bring them to a land of plenty - there aren't enough feeding stations in these locations, either. Hunger has also driven many of the vultures out of Spain and into areas where they are not native. SPIEGEL Media Menü SPIEGEL Media aufklappenįarmers who were previously happy to leave dead animals to the scavengers are less keen to see the birds come after living animals and have called on Spanish officials to increase pressure on EU officials to amend the regulation.Alle Magazine Menü Alle Magazine aufklappen.SPIEGEL-Heft Menü SPIEGEL-Heft aufklappen.Gutscheine Anzeige Menü Gutscheine aufklappen.Marktplatz Anzeige Menü Marktplatz aufklappen.Wissenschaft Menü Wissenschaft aufklappen. Formel 1 – Liveticker, Kalender, WM-Stand.
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