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

Singh, NJ and Ecke, F and Katzner, T and Bagchi, S and Sandström, P and Hörnfeldt, B (2021) Consequences of migratory coupling of predators and prey when mediated by human actions. In: Diversity and Distributions, 27 (9). pp. 1848-1860.

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Abstract

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. © 2021 The Authors. Diversity and Distributions published by John Wiley & Sons Ltd.

Item Type:	Journal Article
Publication:	Diversity and Distributions
Publisher:	Blackwell Publishing Ltd
Additional Information:	The copyright for this article belongs to Authors
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	02 Sep 2021 09:18
Last Modified:	02 Sep 2021 09:18
URI:	http://eprints.iisc.ac.in/id/eprint/69628

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