DOI: 10.5061/dryad.rbnzs7hbp
title: Consequences of migratory coupling of predators and prey when mediated by human actions

description: 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 the 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 if 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 eight 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 kilometers 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.
description: GPS tracking of Golden Eagles, Spatial Mapping of Semi domestic
 Reindeer Calving areas, National Hunting Statistics for Moose
description: In Data file data.csv date - date and time of eagle
 position (YYYY-MM-DD HH:MM:SS)<br> Distance - net squared distance
 between consecutive golden eagle locations  =
 (sqrt(distance/1000000))       <br> Object_ID - Individual eagle
 ID       <br> CalvingOrNot - Whether a position is within the
 calving period or not<br> CalvingPresence - Whether a position is
 within a calving area or not         <br> mooseDenVals - value of
 moose harvest encountered at a eagle's position in terms of No. of
 moose harvested / 1000 ha. (note that this value turns to 0 outside the
 moose hunting season)        <br> MooseHuntOrNot - Whether a
 position is within the moose hunting period or not    <br> AgeClass
 - Whether an individual was a juvenile or adult
 Reindeer calving areas polygons are available
 at https://ext-geodatakatalog.lansstyrelsen.se/GeodataKatalogen/  National moose hunting statistics can be downloaded from https://rapport.viltdata.se/statistik/