SREL Reprint #3580

Network structure of vertebrate scavenger assemblages at the global scale: drivers of ecosystem functioning implications

Esther Sebastián-González1, Zebensui Morales-Reyes1, Francisco Botella1, Lara Naves-Alegre1,
Juan M. Pérez-García1,26, Patricia Mateo-Tomás2, Pedro P. Olea3, Marcos Moleón4, Jomar M. Barbosa5,
Fernando Hiraldo5, Eneko Arrondo5, José A. Donázar5, Ainara Cortés-Avizanda5,6, Nuria Selva7,
Sergio A. Lambertucci8, Aishwarya Bhattacharjee9, Alexis L. Brewer9, Erin F. Abernethy11,
Kelsey L. Turner12, James C. Beasley12, Travis L. DeVault12, Hannah C. Gerke12, Olin E. Rhodes Jr13,
Andrés Ordiz14, Camilla Wikenros15, Barbara Zimmermann16, Petter Wabakken16, Christopher C. Wilmers17,
Justine A. Smith18, Corinne J. Kendall19, Darcy Ogada20, Ethan Frehner21, Maximilian L. Allen22,
Heiko U. Wittmer23, James R. A. Butler24, Johan T. du Toit25, Antoni Margalida26,27, Pilar Oliva-Vidal26,
David Wilson28, Klemen Jerina29, Miha Krofel29, Rich Kostecke30,Richard Inger31, Esra Per32,33,
Yunus Ayhan33, Hasan Ulusoy33, Doganay Vural33, Akino Inagaki34, Shinsuke Koike34,
Arockianathan Samson35, Paula L. Perrig36, Emma Spencer37, Thomas M. Newsome37, Marco Heurich38,
José D. Anadón9,10, Evan R. Buechley39, and José A. Sánchez-Zapata1

1Dept of Applied Biology, Univ. Miguel Hernández, Elche, Spain
2Biodiversity Research Unit (UMIB), UO-CSIC-PA, Oviedo Univ., Mieres, Spain, and
Centre for Functional Ecology, Dept of Life Sciences, Univ. of Coimbra, Coimbra, Portugal
3Depto de Ecología, Univ. Autónoma de Madrid, Madrid, Spain, and Centro de Investigación en
Biodiversidad y Cambio Global (CIBC-UAM), Univ. Autónoma de Madrid, Madrid, Spain
4Dept of Zoology, Univ. of Granada, Granada, Spain
5Dept of Conservation Biology, Doñana Biological Station-CSIC, Seville, Spain
6Animal Ecology and Demography Group, IMEDEA (CSIC-UIB), Esporles, Spain
7Inst. of Nature Conservation, Polish Academy of Sciences, Krakow, Poland
8Grupo de Investigaciones en Biología de la Conservación, Laboratorio Ecotono, INIBIOMA
(CONICET, Univ. Nacional del Comahue), Bariloche, Argentina
9Dept of Biology, Queens College, City Univ. of New York, Queens, NY, USA, and
Biology Program, The Graduate Center, City Univ. of New York, New York, NY, USA
10Depto de Ciencias Agrarias y el Medio Natural, Univ. de Zaragoza. Huesca, Spain
11Dept of Integrative Biology, Oregon State University, Corvallis, OR, USA
12Savannah River Ecology Lab, Warnell School of Forestry and Natural Resources,
Univ. of Georgia, Aiken, SC, USA
13Savannah River Ecology Laboratory, Odum School of Ecology, Univ. of Georgia, Aiken, SC, USA
14Faculty of Environmental Sciences and Natural Resource Management,
Norwegian Univ. of Life Sciences, Ås, Norway
15Grimsö Wildlife Research Station, Dept of Ecology, Swedish Univ. of Agricultural Sciences,
Riddarhyttan, Sweden
16Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Campus Evenstad,
Inland Norway Univ. of Applied Sciences, Norway
17Center for Integrated Spatial Research, Environmental Studies Dept,
Univ. of California, Santa Cruz, CA, USA
18Dept of Wildlife, Fish, and Conservation Biology, Univ. of California, Davis, CA, USA
19North Carolina Zoo, Asheboro, NC, USA
20The Peregrine Fund, Boise, ID, USA
21Dept of Biology, Univ. of Utah, Salt Lake City, UT, USA
22Illinois Natural History Survey, Univ. of Illinois, Champaign, IL, USA
23School of Biological Sciences, Victoria Univ. of Wellington, Wellington, New Zealand
24CSIRO Land and Water, Brisbane, QLD, Australia
25Dept of Wildland Resources, Utah State Univ., Logan, UT, USA
26Dept of Animal Science, Faculty of Life Sciences and Engineering, Univ. of Lleida, Lleida, Spain
27Inst. de Investigación en Recursos Cinegéticos (IREC, CSIC-UCLM-JCCM), Ciudad Real, Spain
28The Biodiversity Consultancy, Cambridge, UK
29Biotechnical Faculty, Univ. of Ljubljana, Ljubljana, Slovenia
30The Nature Conservancy, Austin, TX, USA
31Environment and Sustainability Inst., Univ. of Exeter, Penryn, UK
32Faculty of Science, Dept of Biology, Gazi Univ., Teknikokullar, Ankara, Turkey
33DEDE Nature Team, Yenimahalle Ankara, Turkey
34Dept of Environment Conservation, Tokyo Univ. of Agriculture and Technology, Fuchu, Tokyo, Japan
35Bombay Natural History Society, Mumbai, India
36Dept of Forest and Wildlife Ecology, Univ. of Wisconsin-Madison, WI, USA
37School of Life and Environmental Sciences, The Univ. of Sydney, Sydney, Australia
38Dept of Visitor Management and National Park Monitoring, Bavarian Forest National Park, Grafenau,
Germany, and Chair of Wildlife Ecology and Management, Univ. of Freiburg, Freiburg, Germany
39Smithsonian Migratory Bird Center, Washington, DC, USA, and
HawkWatch International, Salt Lake City, UT, USA

Abstract: The organization of ecological assemblages has important implications for ecosystem functioning, but little is known about how scavenger communities organize at the global scale. Here, we test four hypotheses on the factors affecting the network structure of terrestrial vertebrate scavenger assemblages and its implications on ecosystem functioning. We expect scavenger assemblages to be more nested (i.e. structured): 1) in species-rich and productive regions, as nestedness has been linked to high competition for carrion resources, and 2) regions with low human impact, because the most efficient carrion consumers that promote nestedness are large vertebrate scavengers, which are especially sensitive to human persecution. 3) We also expect climatic conditions to affect assemblage structure, because some scavenger assemblages have been shown to be more nested in colder months. Finally, 4) we expect more organized assemblages to be more efficient in the consumption of the resource. We first analyzed the relationship between the nestedness of the scavenger assemblages and climatic variables (i.e. temperature, precipitation, temperature variability and precipitation variability), ecosystem productivity and biomass (i.e. NDVI) and degree of human impact (i.e. human footprint) using 53 study sites in 22 countries across five continents. Then, we related structure (i.e. nestedness) with its function (i.e. carrion consumption rate). We found a more nested structure for scavenger assemblages in regions with higher NDVI values and lower human footprint. Moreover, more organized assemblages were more efficient in the consumption of carrion. However, our results did not support the prediction that the structure of the scavenger assemblages is directly related to climate. Our findings suggest that the nested structure of vertebrate scavenger assemblages affects its functionality and is driven by anthropogenic disturbance and ecosystem productivity worldwide. Disarray of scavenger assemblage structure by anthropogenic disturbance may lead to decreases in functionality of the terrestrial ecosystems via loss of key species and trophic facilitation processes.

Keywords: carrion, consumption rate, ecological networks, global change, macroecology, NDVI

SREL Reprint #3580

Sebastián-González, E., Z. Morales-Reyes, F. Botella, L. Naves-Alegre, J. M. Pérez-García, P. Mateo-Tomás, P. P. Olea, M. Moleón, J. M. Barbosa, F. Hiraldo, E. Arrondo, J. A. Donázar, A. Cortés-Avizanda, N. Selva, S. A. Lambertucci, A. Bhattacharjee, A. Brewer, E. Abernethy, K. Turner, J. C. Beasley, T. L. DeVault, H. Gerke, O. E. Rhodes Jr, A. Ordiz, C. Wikenros, B. Zimmermann, P. Wabakken, C. C. Wilmers, J. A. Smith, C. J. Kendall, D. Ogada, E. Frehner, M. L. Allen, H. U. Wittmer, J. R. A. Butler, J. T. du Toit, A. Margalida, P. Olivia-Vidal, D. Wilson, K. Jerina, M. Krofel, R. Kostecke, R. Inger, E. Per, Y. Ayhan, H. Ulusoy, D. Vural, A. Inagaki, S. Koike, A. Samson, P. L. Perrig, E. Spencer, T. M. Newsome, M. Heurich, J. D. Anadón, E. R. Beuchley, and J. A. Sánchez-Zapata. 2020. Network structure of vertebrate scavenger assemblages at the global scale: drivers of ecosystem functioning implications. Ecography 43:1-13, doi:10.1111/ecog.05083.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).