Using GPS tracking data to validate the conservation value of bird migration counts

Ron Efrat, Yael Lehnardt, Daniel Berkowic, Yossi Leshem, Roi Dor, Alexander Bragin, Evgeny Bragin, Todd Katzner, Nir Sapir

Research output: Contribution to journalArticlepeer-review

Abstract

Effective conservation of migratory birds requires gathering of information about their population trends, often acquired using migratory bird counts. These schemes ideally operate at migratory bottlenecks, through which a significant portion of the counted migratory populations is funneled. Yet it is rare to validate the conservation value of the data from these counts. Here we perform this validation using GPS tracking data collected from two migratory species during their movement over two count schemes: the globally endangered steppe eagle counted in Eilat, Israel, and the black kite, counted in Batumi, Georgia. We use tracking data to answer two questions: which populations are counted and what affects the probability that a given individual will be counted. Our results illustrate variability in the effectiveness of these two migratory bird counting schemes. Considering the goal of estimating population trends, we show that Eilat does not represent a good location for understanding population trends of steppe eagles, while Batumi appears to provide better information on demographic trends of black kites. We further present differences in annual and individual variability, evidence regarding the breeding area origins of the counted populations and effects of environmental factors on the raptors' routes and, consequently, on the probabilities of being counted. Beyond the direct implications of our results, this study provides an example of using telemetry data to parameterize inference from bird counts. Further coupling of migratory bird count data and GPS data can improve our understanding of migration ecology and the conservation of migratory species.

Original languageEnglish
Article number110959
JournalBiological Conservation
Volume302
DOIs
StatePublished - Feb 2025

Bibliographical note

Publisher Copyright:
© 2025 Elsevier Ltd

Keywords

  • Biologging
  • Black kite
  • Citizen science
  • Conservation ecology
  • Monitoring
  • Movement ecology
  • Steppe eagle

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