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Gámez S, Potts A, Mills KL, Allen AA, Holman A, Randon PM, Linson O, Harris NC. Downtown diet: a global meta-analysis of increased urbanization on the diets of vertebrate predators. Proc Biol Sci 2022; 289:20212487. [PMID: 35232241 PMCID: PMC8889190 DOI: 10.1098/rspb.2021.2487] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Predation is a fundamental ecological process that shapes communities and drives evolutionary dynamics. As the world rapidly urbanizes, it is critical to understand how human perturbations alter predation and meat consumption across taxa. We conducted a meta-analysis to quantify the effects of urban environments on three components of trophic ecology in predators: dietary species richness, dietary evenness and stable isotopic ratios (IRs) (δ13C and δ15N IR). We evaluated whether the intensity of anthropogenic pressure, using the human footprint index (HFI), explained variation in effect sizes of dietary attributes using a meta-regression. We calculated Hedges' g effect sizes from 44 studies including 11 986 samples across 40 predatory species in 39 cities globally. The direction and magnitude of effect sizes varied among predator taxa with reptilian diets exhibiting the most sensitivity to urbanization. Effect sizes revealed that predators in cities had comparable diet richness, evenness and nitrogen ratios, though carbon IRs were more enriched in cities. We found that neither the 1993 nor 2009 HFI editions explained effect size variation. Our study provides, to our knowledge, the first assessment of how urbanization has perturbed predator-prey interactions for multiple taxa at a global scale. We conclude that the functional role of predators is conserved in cities and urbanization does not inherently relax predation, despite diets broadening to include anthropogenic food sources such as sugar, wheat and corn.
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Affiliation(s)
- Siria Gámez
- Applied Wildlife Ecology Laboratory, School of the Environment, Yale University, 195 Prospect Street, New Haven, CT 06511, USA
| | - Abigail Potts
- Ecology and Evolutionary Biology, University of Michigan, 500 S State Street #2005, Ann Arbor, MI 48109, USA
| | - Kirby L Mills
- Ecology and Evolutionary Biology, University of Michigan, 500 S State Street #2005, Ann Arbor, MI 48109, USA
| | - Aurelia A Allen
- Ecology and Evolutionary Biology, University of Michigan, 500 S State Street #2005, Ann Arbor, MI 48109, USA
| | - Allyson Holman
- School for Environment and Sustainability, University of Michigan, 500 S State Street #2005, Ann Arbor, MI 48109, USA
| | - Peggy M Randon
- Ecology and Evolutionary Biology, University of Michigan, 500 S State Street #2005, Ann Arbor, MI 48109, USA
| | - Olivia Linson
- College of Literature, Science and the Arts, University of Michigan, 500 S State Street #2005, Ann Arbor, MI 48109, USA
| | - Nyeema C Harris
- Applied Wildlife Ecology Laboratory, School of the Environment, Yale University, 195 Prospect Street, New Haven, CT 06511, USA
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Josiah KK, Downs CT. Human-wildlife interactions: presence of the ground-nesting Spotted Thick-knee across a South African mosaic urban landscape. Urban Ecosyst 2022; 25:1631-1641. [PMID: 35754656 PMCID: PMC9207825 DOI: 10.1007/s11252-022-01254-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2022] [Indexed: 12/14/2022]
Abstract
Urbanisation has increasingly encroached on numerous bird species' natural habitats, generally negatively affecting their persistence. Furthermore, increased human-wildlife interactions may benefit or be detrimental to the long term persistence of these species. The Spotted Thick-knee (Burhinus capensis), a ground-nesting species, persists in some mosaic urban landscapes in South Africa. We, therefore, assessed the presence of Spotted Thick-knees and their interactions with humans in the fragmented natural and human-modified landscape of Pietermaritzburg, KwaZulu-Natal. We conducted presence-only surveys at 52 locations between July 2019 and December 2020. 'Presence' locations for Spotted Thick-knee were identified via active surveying and public participation. Newspaper articles were distributed in June 2019, requesting information on Spotted Thick-knee sightings. Questionnaires were also sent to respondents to collect qualitative information regarding their perceptions and observations of this species in Pietermaritzburg. We established that the presence of Spotted Thick-knee's at known locations was not random. They were present at 30 out of 52 sites for 75% of this study's duration. Fewer sites had Spotted Thick-knees present during non-breeding months than breeding months. Respondents' feedback highlighted the pressures associated with Spotted Thick-knees persistence in human-modified mosaic landscapes, particularly predation and disturbance by domestic pets. Our study highlights that some ground-nesting birds, such as Spotted Thick-knees, persist in mosaic urban landscapes, despite the anthropogenic pressures. This study highlights the need to address the paucity of studies on ground-nesting birds in mosaic urban landscapes to determine general trends. Supplementary information The online version contains supplementary material available at 10.1007/s11252-022-01254-3.
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Affiliation(s)
- Kyrone K. Josiah
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209 South Africa
| | - Colleen T. Downs
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209 South Africa
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