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Carcass Provisioning for Scavenger Conservation in a Temperate Forest Ecosystem

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Carcass Provisioning for Scavenger Conservation in a Temperate Forest Ecosystem Mathematisch-Naturwissenschaftliche Fakultät Jonas Stiegler | Christian von Hoermann | Jörg Müller | Mark Eric Benbow | Marco Heurich Carcass provisioning for scavenger conservation in a temperate forest ecosystem Suggested citation referring to the original publication: Ecosphere 11 (2020) 4, e03063 DOI https://doi.org/110.1002/ecs2.3063 ISSN (online) 2150-8925 Postprint archived at the Institutional Repository of the Potsdam University in: Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe ; 955 ISSN 1866-8372 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus4-471099 DOI https://doi.org/10.25932/publishup-47109 Carcass provisioning for scavenger conservation in a temperate forest ecosystem 1, 2 € € 3 JONAS STIEGLER , CHRISTIAN VON HOERMANN , JORG MULLER , 4,5,6 2 M. ERIC BENBOW , AND MARCO HEURICH 1Department of Plant Ecology and Nature Conservation, University of Potsdam, Potsdam, Germany 2Department of Wildlife Ecology and Management, University of Freiburg, Freiburg, Germany 3Department of Animal Ecology and Tropical Biology, University of Wurzburg,€ Wurzburg,€ Germany 4Department of Entomology, Michigan State University, East Lansing, Michigan, USA 5Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan, USA 6Ecology, Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, Michigan, USA Citation: Stiegler, J., C. von Hoermann, J. Muller,€ M. E. Benbow, and M. Heurich. 2020. Carcass provisioning for scavenger conservation in a temperate forest ecosystem. Ecosphere 11(4):e03063. 10.1002/ecs2.3063 Abstract. Carrion plays an essential role in shaping the structure and functioning of ecosystems and has far-reaching implications for biodiversity conservation. The change in availability and type of carcasses throughout ecosystems can involve negative effects for scavenging communities. To address this issue, there have been recent conservation management measures of carrion provision in natural systems. How- ever, the optimal conditions under which exposing carcasses to optimize conservation outcomes are still limited. Here, we used camera traps throughout elevational and vegetational gradients to monitor the con- sumption of 48 deer carcasses over a study period of six years by evaluating 270,279 photographs resulting out of 15,373 trap nights. We detected 17 species visiting carcass deployments, including five endangered species. Our results show that large carcasses, the winter season, and a heterogeneous surrounding habitat enhanced the frequency of carcass visits and the species richness of scavenger assemblages. Contrary to our expectations, carcass species, condition (fresh/frozen), and provision schedule (continuous vs single exposure) did not influence scavenging frequency or diversity. The carcass visitation frequency increased with carcass mass and lower temperatures. The effect of large carcasses was especially pronounced for mesopredators and the Eurasian lynx (Lynx lynx). Lynx were not too influenced in its carrion acquisition by the season, but exclusively preferred remote habitats containing higher forest cover. Birds of prey, meso- predators, and top predators were also positively influenced by the visiting rate of ravens (Corvus corax), whereas no biotic or abiotic preferences were found for wild boars (Sus scrofa). This study provides evi- dence that any ungulate species of carrion, either in a fresh or in previously frozen condition, attracts a high diversity of scavengers especially during winter, thereby supporting earlier work that carcass provi- sions may support scavenger communities and endangered species. Key words: anthropogenic food subsidies; carrion ecology; diversity; nature conservation; necrobiome; vertebrate scavenger; wildlife management. Received 25 November 2019; revised 8 January 2020; accepted 14 January 2020. Corresponding Editor: Robert R. Parmenter. Copyright: © 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. E-mail: [email protected] INTRODUCTION of food web trophic links worldwide (Wilson and Wolkovich 2011). Individual carrion has Scavenging of animal carcasses is an important been viewed as “cadaver decomposition islands” ecological process that is reported to affect 45% (Carter et al. 2007) or as “ephemeral resource ❖ www.esajournals.org 1 April 2020 ❖ Volume 11(4) ❖ Article e03063 STIEGLER ET AL. patches” (Finn 2001) that create spatially distinct 2009, Estes et al. 2011) and management prac- hotspots of biological activity through both tices such as winter feeding of ungulates like roe direct and indirect interactions of many necro- deer (Capreolus capreolus; Ossi et al. 2017) or red phagous species (Finn 2001, Barton et al. 2013b, deer (Cervus elaphus; Putman and Staines 2004), Benbow et al. 2018). As a part of this necropha- the spatial and temporal availability of natural gous network, vertebrate scavengers provide carrion resources has also decreased in many both supporting and regulating ecosystem ser- regions, having far-reaching negative conse- vices through nutrient cycling and carcass quences for scavenger communities (Wilmers removal from the landscape that mediates habi- et al. 2003a, Selva et al. 2005, Cortes-Avizanda tat quality (DeVault et al. 2003, Parmenter and et al. 2016). In the few instances where top MacMahon 2009, Benbow et al. 2015). Most predators have increased, scavenger populations available carcasses are successfully scavenged if and communities have benefited. For example, they are found before extensive decomposition the reintroduction of wolves in Yellowstone by microbes and insects occurs (Putman 1983). National Park (USA) in 1995 led to an increase in Depending on environmental conditions, scav- abundance of 13 species of scavengers through enging vertebrates can account for up to 90% of the regular supply of carrion from gray wolf kills the carrion biomass assimilation (Houston 1986, (Canis lupus; Wilmers et al. 2003a,b). Also benefi- DeVault et al. 2011). Thus, carrion plays an cial effects of regular carcass supply are shown important role in scavenger ecology, especially by Margalida et al. (2007), who found that breed- during times of the year with limited alternative ing effort of the Eurasian griffon vulture (Gyps food sources (Selva et al. 2003, 2005). fulvus) and the Egyptian vulture (Neophron perc- In attempts to support populations of scav- nopterus) in Catalonia (Spain) was linked to car- enger species, land and wildlife managers have rion availability. adopted the practice of provisioning carcasses Carrion undoubtedly provides feeding oppor- of wild or domestic herbivores in several tunities for a variety of species (Cortes-Avizanda ecosystems (Gilbert et al. 2007, John Muir Trust et al. 2009, 2016), but to understand its role in 2012), exemplified by the prominent supple- nature conservation, including in the reintroduc- mentary feeding stations acting as important tion of carrion-dependent species in areas where tools for conservation and supporting avian they have become extinct, a better understanding scavengers (Cortes-Avizanda et al. 2016). Eco- of carcass provision conditions is needed (Field- logical experiments have shown that providing ing et al. 2014). A comparison of the general carcasses can favor the coexistence of competi- structure of scavenger communities in response tors (Barton et al. 2013a, Benbow et al. 2018) to carrion provision will advance conservation and facilitate the formation of metacommunities efforts related to anthropogenic food subsidies to in and around the resource (Leibold et al. ecosystems (Oro et al. 2013). However, little is 2004). However, the optimal frequency and con- known about the effects of intentionally placed ditions of carrion provision are not well under- carcasses as a management tool in supporting stood and may be influenced by both local and vertebrate scavenger communities (Turner et al. regional environmental (e.g., biotic and abiotic) 2017). For instance, how do carcass species, size, conditions. condition, and introduced habitat affect scav- Due to the rapidly expanding human footprint enger diversity and activity? (Venter et al. 2016), the availability of carcasses is One major factor affecting vertebrate scaveng- changing worldwide. Actual numbers are rising ing is carcass size (DeVault et al. 2003, Sebastian- in certain cases, for example, through intensive Gonzalez et al. 2013). In a study conducted in animal farming or hunting (Margalida et al. the South African savanna, the species richness 2012, Oro et al. 2013, Mateo-Tomas et al. 2015). of vertebrate scavengers and carcass consump- Additionally, the successful recovery of large car- tion time and rate increased with carcass size nivores (Chapron et al. 2014) could also con- (Moleon et al. 2015). In south-central Scandi- tribute to a local increase of the availability of navia, carcasses of moose (Alces alces) were less carcasses. But owing to both the ongoing decline likely to be visited by scavengers as carcass bio- of top predators in most ecosystems (Prugh et al. mass decreased (Wikenros et al. 2013). ❖ www.esajournals.org 2 April 2020 ❖ Volume 11(4) ❖ Article e03063 STIEGLER ET AL. Another factor affecting scavenging is the the proliferation of microorganisms within and physical condition of the carcass, namely on carcasses (Benbow et al. 2013,
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