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Barbosa JM, Hiraldo F, Romero MÁ, Tella JL. When does agriculture enter into conflict with wildlife? A global assessment of parrot–agriculture conflicts and their conservation effects. DIVERS DISTRIB 2020. [DOI: 10.1111/ddi.13170] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Jomar M. Barbosa
- Department of Conservation Biology Estación Biológica de DoñanaC.S.I.C. Seville Spain
| | - Fernando Hiraldo
- Department of Conservation Biology Estación Biológica de DoñanaC.S.I.C. Seville Spain
| | - Miguel Á. Romero
- Department of Conservation Biology Estación Biológica de DoñanaC.S.I.C. Seville Spain
| | - José L. Tella
- Department of Conservation Biology Estación Biológica de DoñanaC.S.I.C. Seville Spain
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Morris DW. Time-averaging voles match density with long-term habitat quality. Ecology 2020; 101:e03036. [PMID: 32129877 DOI: 10.1002/ecy.3036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 01/28/2020] [Accepted: 02/06/2020] [Indexed: 11/11/2022]
Abstract
An optimal habitat-selecting organism should use a dispersal strategy that enables occupation of the habitat yielding greatest fitness. The strategy is complicated when habitat quality varies through time. Theory predicts that the long-term distribution of individuals will match mean habitat quality while undermatching current habitat quality. I tested the prediction with experiments on controlled populations of meadow voles occupying two pairs of field enclosures. I released equal numbers, and equal sexes, of voles in each enclosure, and varied resource abundance between enclosures by supplemental feeding. I measured the voles' response with giving-up densities (GUDs) in artificial foraging patches, and with live-trapping at the end of the experiment. The data were consistent with only one of four a priori dispersal models. Giving-up densities declined with resource supply because short-term supply had no effect on population density. GUDs were invariant to the time course of the experiment because densities were proportional to each enclosure's long-term mean quality. Similar patterns in sex ratios and patterns of habitat occupation by juvenile voles born during the experiment reinforce the interpretation of time-averaged habitat matching. This study adds to the cumulating evidence that strategies of space use converge toward behavioral and evolutionary optima.
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Affiliation(s)
- Douglas W Morris
- Department of Biology, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada
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Bonin M, Dussault C, Côté SD. Increased trophic position of black bear (Ursus americanus) at the northern fringe of its distribution range. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2019-0062] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Studies describing the diet of omnivorous species are abundant, but the drivers affecting the balance between animal and plant resources remain unclear. Among those drivers, latitude has been reported to positively correlate with the trophic position of consumers. Using stable isotope analysis, we tested the hypothesis that trophic position of black bears (Ursus americanus Pallas, 1780) is positively correlated with latitude in eastern North America. We sampled 57 bears over a 15° latitudinal gradient in Quebec, Canada, and used stable isotope analysis to assess individual trophic position and metrics of dietary niches. We found a strong positive correlation between trophic position of bears and latitude (r2 = 0.76), which persisted throughout seasons. The width of the dietary niche of bears also appeared to follow a latitudinal pattern, even though bears foraging at the southernmost part of the gradient also showed a wide dietary niche. The impact of latitude on the foraging tactic of omnivores fosters our understanding of their capability to deal with contrasting environmental conditions, especially for species whose distribution ranges are expanding due to climate change. The flexibility of black bear foraging tactic likely allows this species to expand its geographical distribution range toward northern habitats.
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Affiliation(s)
- Michaël Bonin
- Caribou Ungava, département de biologie, Centre d’études nordiques, Université Laval, 1045, avenue de la Médecine, Québec, QC G1V 0A6, Canada
| | - Christian Dussault
- Caribou Ungava, département de biologie, Centre d’études nordiques, Université Laval, 1045, avenue de la Médecine, Québec, QC G1V 0A6, Canada
- Direction de l’expertise sur la faune terrestre, l’herpétofaune et l’avifaune, Ministère des Forêts, de la Faune et des Parcs, 880, chemin Sainte-Foy, Québec, QC G1S 4X4, Canada
| | - Steeve D. Côté
- Caribou Ungava, département de biologie, Centre d’études nordiques, Université Laval, 1045, avenue de la Médecine, Québec, QC G1V 0A6, Canada
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Michel VT, Jiménez‐Franco MV, Naef‐Daenzer B, Grüebler MU. Intraguild predator drives forest edge avoidance of a mesopredator. Ecosphere 2016. [DOI: 10.1002/ecs2.1229] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Vanja T. Michel
- Swiss Ornithological Institute CH‐6204 Sempach Switzerland
- Institute of Evolutionary Biology and Environmental StudiesUniversity of Zurich CH‐8057 Zurich Switzerland
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Fondo EN, Chaloupka M, Heymans JJ, Skilleter GA. Banning Fisheries Discards Abruptly Has a Negative Impact on the Population Dynamics of Charismatic Marine Megafauna. PLoS One 2015; 10:e0144543. [PMID: 26657412 PMCID: PMC4676608 DOI: 10.1371/journal.pone.0144543] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 11/19/2015] [Indexed: 11/25/2022] Open
Abstract
Food subsidies have the potential to modify ecosystems and affect the provision of goods and services. Predictable Anthropogenic Food Subsidies (PAFS) modify ecosystems by altering ecological processes and food webs. The global concern over the effects of PAFS in ecosystems has led to development of environmental policies aimed at curbing the production or ultimately banning of PAFS. However, the effects of reducing or banning PAFS are not known. We explore the consequences of PAFS removal in a marine ecosystem under two scenarios: 1) gradual reduction, or 2) an abrupt ban, using a mass balance model to test these hypotheses–The reduction or loss of PAFS will: i) modify trophic levels and food webs through effects on foraging by opportunistic species, ii) increase the resilience of opportunistic species to food shortages, and iii) modify predator–prey interactions through shifts in prey consumption. We found that PAFS lower the trophic levels of opportunistic scavengers and increase their food pathways. Scavengers are able to switch prey when PAFS are reduced gradually but they decline when PAFS are abruptly banned. PAFS reduction to a certain minimal level causes a drop in the ecosystem’s stability. We recommend gradual reduction of PAFS to a minimal level that would maintain the ecosystem’s stability and allow species exploiting PAFS to habituate to the food subsidy reduction.
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Affiliation(s)
- Esther N. Fondo
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
- Kenya Marine and Fisheries Research Institute, Mombasa, Kenya
- * E-mail: (ENF); (GAS)
| | - Milani Chaloupka
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Johanna J. Heymans
- The Scottish Association for Marine Science, Oban, Scotland, United Kingdom
| | - Greg A. Skilleter
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
- * E-mail: (ENF); (GAS)
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Trewby ID, Young R, McDonald RA, Wilson GJ, Davison J, Walker N, Robertson A, Doncaster CP, Delahay RJ. Impacts of removing badgers on localised counts of hedgehogs. PLoS One 2014; 9:e95477. [PMID: 24736454 PMCID: PMC3988185 DOI: 10.1371/journal.pone.0095477] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 03/27/2014] [Indexed: 12/02/2022] Open
Abstract
Experimental evidence of the interactions among mammalian predators that eat or compete with one another is rare, due to the ethical and logistical challenges of managing wild populations in a controlled and replicated way. Here, we report on the opportunistic use of a replicated and controlled culling experiment (the Randomised Badger Culling Trial) to investigate the relationship between two sympatric predators: European badgers Meles meles and western European hedgehogs Erinaceus europaeus. In areas of preferred habitat (amenity grassland), counts of hedgehogs more than doubled over a 5-year period from the start of badger culling (from 0.9 ha−1 pre-cull to 2.4 ha−1 post-cull), whereas hedgehog counts did not change where there was no badger culling (0.3–0.3 hedgehogs ha−1). This trial provides experimental evidence for mesopredator release as an outcome of management of a top predator.
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Affiliation(s)
- Iain D. Trewby
- National Wildlife Management Centre, Animal Health and Veterinary Laboratories Agency, New Haw, Addlestone, United Kingdom
- * E-mail:
| | - Richard Young
- Durrell Wildlife Conservation Trust, Les Augrès Manor Trinity, Jersey, Channel Islands, United Kingdom
| | - Robbie A. McDonald
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, United Kingdom
| | - Gavin J. Wilson
- National Wildlife Management Centre, Animal Health and Veterinary Laboratories Agency, New Haw, Addlestone, United Kingdom
| | - John Davison
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | - Neil Walker
- National Wildlife Management Centre, Animal Health and Veterinary Laboratories Agency, New Haw, Addlestone, United Kingdom
| | - Andrew Robertson
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, United Kingdom
| | - C. Patrick Doncaster
- Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Richard J. Delahay
- National Wildlife Management Centre, Animal Health and Veterinary Laboratories Agency, New Haw, Addlestone, United Kingdom
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Root-Bernstein M, Fierro A, Armesto J, Ebensperger LA. Avian ecosystem functions are influenced by small mammal ecosystem engineering. BMC Res Notes 2013; 6:549. [PMID: 24359802 PMCID: PMC3878134 DOI: 10.1186/1756-0500-6-549] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 12/09/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Birds are important mobile link species that contribute to landscape-scale patterns by means of pollination, seed dispersal, and predation. Birds are often associated with habitats modified by small mammal ecosystem engineers. We investigated whether birds prefer to forage on degu (Octodon degus) runways by comparing their foraging effort across sites with a range of runway densities, including sites without runways. We measured granivory by granivorous and omnivorous birds at Rinconada de Maipú, central Chile. As a measure of potential bird foraging on insects, we sampled invertebrate prey richness and abundance across the same sites. We then quantified an index of plot-scale functional diversity due to avian foraging at the patch scale. RESULTS We recorded that birds found food sources sooner and ate more at sites with higher densities of degu runways, cururo mounds, trees, and fewer shrubs. These sites also had higher invertebrate prey richness but lower invertebrate prey abundance. This implies that omnivorous birds, and possibly insectivorous birds, forage for invertebrates in the same plots with high degu runway densities where granivory takes place. In an exploratory analysis we also found that plot-scale functional diversity for four avian ecosystem functions were moderately to weakly correllated to expected ecosystem function outcomes at the plot scale. CONCLUSIONS Degu ecosystem engineering affects the behavior of avian mobile link species and is thus correlated with ecosystem functioning at relatively small spatial scales.
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Affiliation(s)
- Meredith Root-Bernstein
- Department of Ecology, Facultad de Ciencias Biologicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Oxford University Centre for the Environment, School of Geography and the Environment, Oxford University, Oxford, UK
| | - Andres Fierro
- Department of Ecological Sciences, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Juan Armesto
- Department of Ecology, Facultad de Ciencias Biologicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Institute of Ecology and Biodiversity, Box 653, Santiago, Chile
| | - Luis A Ebensperger
- Department of Ecology, Facultad de Ciencias Biologicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Dupuch A, Morris DW, Halliday WD. Patch use and vigilance by sympatric lemmings in predator and competitor-driven landscapes of fear. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1645-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Oro D, Genovart M, Tavecchia G, Fowler MS, Martínez-Abraín A. Ecological and evolutionary implications of food subsidies from humans. Ecol Lett 2013; 16:1501-14. [PMID: 24134225 DOI: 10.1111/ele.12187] [Citation(s) in RCA: 343] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/15/2013] [Accepted: 08/23/2013] [Indexed: 11/28/2022]
Abstract
Human activities are the main current driver of global change. From hunter-gatherers through to Neolithic societies-and particularly in contemporary industrialised countries-humans have (voluntarily or involuntarily) provided other animals with food, often with a high spatio-temporal predictability. Nowadays, as much as 30-40% of all food produced in Earth is wasted. We argue here that predictable anthropogenic food subsidies (PAFS) provided historically by humans to animals has shaped many communities and ecosystems as we see them nowadays. PAFS improve individual fitness triggering population increases of opportunistic species, which may affect communities, food webs and ecosystems by altering processes such as competition, predator-prey interactions and nutrient transfer between biotopes and ecosystems. We also show that PAFS decrease temporal population variability, increase resilience of opportunistic species and reduce community diversity. Recent environmental policies, such as the regulation of dumps or the ban of fishing discards, constitute natural experiments that should improve our understanding of the role of food supply in a range of ecological and evolutionary processes at the ecosystem level. Comparison of subsidised and non-subsidised ecosystems can help predict changes in diversity and the related ecosystem services that have suffered the impact of other global change agents.
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Affiliation(s)
- Daniel Oro
- Population Ecology Group, IMEDEA (CSIC-UIB), Esporles, 07190, Spain
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Zwolak R, Pearson D, Ortega Y, Crone E. Mechanisms driving postfire abundance of a generalist mammal. CAN J ZOOL 2012. [DOI: 10.1139/z11-111] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Changes in vertebrate abundance following disturbance are commonly attributed to shifts in food resources or predation pressure, but underlying mechanisms have rarely been tested. We examined four hypotheses for the commonly reported increase in abundance of deer mouse ( Peromyscus maniculatus (Wagner, 1845)) following forest fires: source–sink dynamics, decreased predation, increased food resources, and increased foraging efficiency. We found that reproduction of deer mouse was considerably higher in burned versus unburned forests and survival did not differ between habitats, indicating that burned forests were not sink habitats. Comparable survival also suggested that predation rates were similar between habitats. Increased reproduction in burned versus unburned forest suggested better resource conditions, but abundance of seeds and arthropods (the primary food resources for mice) either did not differ between habitats or were higher overall in unburned forest. Foraging experiments indicated that seed removal from depots was substantially higher in burned versus unburned forests after controlling for mouse density. Additionally, in both habitats, mice were captured more often in open microhabitats and the odds of individual insect removal increased with decreasing cover during certain sampling periods. Of the four hypotheses tested, greater foraging efficiency provided the best explanation for elevated populations of deer mouse. However, predation risk may have influenced foraging success.
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Affiliation(s)
- R. Zwolak
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - D.E. Pearson
- U.S. Department of Agriculture (USDA) Forest Service, Rocky Mountain Research Station, 800 East Beckwith Avenue, Missoula, MT 59801, USA; Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Y.K. Ortega
- U.S. Department of Agriculture (USDA) Forest Service, Rocky Mountain Research Station, 800 East Beckwith Avenue, Missoula, MT 59801, USA; Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - E.E. Crone
- Wildlife Biology Program, University of Montana, Missoula, MT 59812, USA
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Edwards MA, Derocher AE, Hobson KA, Branigan M, Nagy JA. Fast carnivores and slow herbivores: differential foraging strategies among grizzly bears in the Canadian Arctic. Oecologia 2010; 165:877-89. [PMID: 21153738 DOI: 10.1007/s00442-010-1869-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 11/23/2010] [Indexed: 10/18/2022]
Abstract
Categorizing animal populations by diet can mask important intrapopulation variation, which is crucial to understanding a species' trophic niche width. To test hypotheses related to intrapopulation variation in foraging or the presence of diet specialization, we conducted stable isotope analysis (δ(13)C, δ(15)N) on hair and claw samples from 51 grizzly bears (Ursus arctos) collected from 2003 to 2006 in the Mackenzie Delta region of the Canadian Arctic. We examined within-population differences in the foraging patterns of males and females and the relationship between trophic position (derived from δ(15)N measurements) and individual movement. The range of δ(15)N values in hair and claw (2.0-11.0‰) suggested a wide niche width and cluster analyses indicated the presence of three foraging groups within the population, ranging from near-complete herbivory to near-complete carnivory. We found no linear relationship between home range size and trophic position when the data were continuous or when grouped by foraging behavior. However, the movement rate of females increased linearly with trophic position. We used multisource dual-isotope mixing models to determine the relative contributions of seven prey sources within each foraging group for both males and females. The mean bear dietary endpoint across all foraging groups for each sex fell toward the center of the mixing polygon, which suggested relatively well-mixed diets. The primary dietary difference across foraging groups was the proportional contribution of herbaceous foods, which decreased for both males and females from 42-76 to 0-27% and 62-81 to 0-44%, respectively. Grizzlies of the Mackenzie Delta live in extremely harsh conditions and identifying within-population diet specialization has improved our understanding of varying habitat requirements within the population.
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Affiliation(s)
- Mark A Edwards
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
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The influence of productivity and width of littoral zone on the trophic position of a large-bodied omnivore. Oecologia 2008; 156:681-90. [PMID: 18368427 DOI: 10.1007/s00442-008-1019-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 02/25/2008] [Indexed: 10/22/2022]
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Zwolak R, Foresman KR. Deer mouse demography in burned and unburned forest: no evidence for source–sink dynamics. CAN J ZOOL 2008. [DOI: 10.1139/z07-126] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Deer mouse ( Peromyscus maniculatus (Wagner, 1845)) populations increase dramatically after wildfires. These increases are puzzling because there are no obvious food sources or vegetation cover in severely burned areas. We conducted a capture–mark–recapture study of deer mice in a mosaic of burned and unburned montane forests in western Montana to determine if their postfire increase could be explained by source–sink dynamics, with burned areas acting as a sink. When overall mouse densities were very low, the vast majority of the population was found in burned areas. Mice appeared regularly in unburned forest only when the densities were high. This pattern is precisely opposite to the expected results if the sink hypothesis were correct. Moreover, mice in burned areas did not show decreased body mass, reproductive performance, or survival when compared with mice in unburned areas. Age structure and sex ratio did not differ between burned and unburned sites. We conclude that burned areas do not function as population sinks; rather, they represent high-quality habitat for deer mice.
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Affiliation(s)
- Rafał Zwolak
- Health Sciences Room 104, Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Kerry R. Foresman
- Health Sciences Room 104, Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA
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Abstract
Trophic level interactions between predators create complex relationships such as intraguild predation. Theoretical research has predicted two possible paths to stability in intraguild systems: intermediate predators either outcompete higher-order predators for shared resources or select habitat based on security. The effects of intraguild predation on intermediate mammalian predators such as swift foxes (Vulpes velox) are not well understood. We examined the relationships between swift foxes and both their predators and prey, as well the effect of vegetation structure on swift fox-coyote (Canis latrans) interactions, between August 2001 and August 2004. In a natural experiment created by the Pinon Canyon Maneuver Site in southeastern Colorado, USA, we documented swift fox survival and density in a variety of landscapes and compared these parameters in relation to prey availability, coyote abundance, and vegetation structure. Swift fox density varied significantly between study sites, while survival did not. Coyote abundance was positively related to the basal prey species and vegetation structure, while swift fox density was negatively related to coyote abundance, basal prey species, and vegetation structure. Our results support the prediction that, under intraguild predation in terrestrial systems, top predator distribution matches resource availability (resource match), while intermediate predator distribution inversely matches predation risk (safety match). While predation by coyotes may be the specific cause of swift fox mortality in this system, the more general mechanism appears to be exposure to predation moderated by shrub density.
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Affiliation(s)
- Craig M Thompson
- Department of Forest, Range, and Wildlife Sciences, Utah State University, Logan, Utah 84322-5210, USA.
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