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Research article - Peer-reviewed, 2021

Consequences of migratory coupling of predators and prey when mediated by human actions

Singh, Navinder J.; Ecke, Frauke; Katzner, Todd; Bagchi, Sumanta; Sandstrom, Per; Hornfeldt, Birger


Aim Animal migrations influence ecosystem structure, dynamics and persistence of predator and prey populations. The theory of migratory coupling postulates that aggregations of migrant prey can induce large-scale synchronized movements in predators, and this coupling is consequential for the dynamics of ecological communities. The degree to which humans influence these interactions remains largely unknown. We tested whether creation of large resource pulses by humans such as seasonal herding of reindeer Rangifer tarandus and hunting of moose, Alces alces, can induce migratory coupling with Golden Eagles, Aquila chrysaetos, and whether these lead to demographic consequences for the eagles. Location Fennoscandia. Methods We used movement data from 32 tracked Golden Eagles spanning 125 annual migratory cycles over 8 years. We obtained reindeer distribution data through collaboration with reindeer herders based on satellite tracking of reindeer, and moose harvest data from the national hunting statistics for Sweden. We assessed demographic consequences for eagles from ingesting lead from ammunition fragments in moose carcasses through survival estimates and their links with lead concentrations in eagles' blood. Results In spring, eagles migrated hundreds of kilometres to be spatially and temporally coupled with calving reindeer, whereas in autumn, eagles matched their distribution with the location and timing of moose hunt. Juveniles were more likely to couple with reindeer calving, whereas adults were particularly drawn to areas of higher moose harvest. Due to this coupling, eagles ingested lead from spent ammunition in moose offal and carcasses and the resulting lead toxicity increased the risk of mortality by 3.4 times. Main conclusions We show how migratory coupling connects landscape processes and that human actions can influence migratory coupling over large spatial scales and increase demographic risks for predators. We provide vital knowledge towards resolving human-wildlife conflicts and the conservation of protected species over a large spatial and temporal scale.


conflict; lead poisoning; migration; predator-prey; reindeer; scale; scavengers; synchrony; toxicology

Published in

Diversity and Distributions
2021, volume: 27, number: 9, pages: 1848-1860
Publisher: WILEY

Authors' information

Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies
Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies
Katzner, Todd
US Geological Survey (USGS)
Bagchi, Sumanta
Indian Institute of Science (IISC) - Bangalore
Swedish University of Agricultural Sciences, Department of Forest Resource Management
Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies

Sustainable Development Goals

SDG15 Life on land

UKÄ Subject classification

Fish and Wildlife Management

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