Competition is a major limiting factor of refueling in migratory passerines during stopover

Sean V. Zimin, Anna Zimin, Darren J. Burns, Rony Livne, Rafi Paz, Yoram Zvik, Eyal Shochat, Ofer Ovadia

Research output: Contribution to journalArticlepeer-review


For an avian migrant, refueling capacity attainable during stopovers governs the entire migration schedule and, ultimately, its fitness. Specifically, timely replenishing energy stores is critical when migration involves crossing ecological barriers, within which refueling may be limited. Here, we tested the hypothesis that fuel deposition rates (FDRs) of migratory passerines within barrier-edge stopover sites are constrained by the density of potential competitors, irrespective of migration season, phenology, and local environmental conditions. We also evaluated diverse intra- and inter-specific competition scenarios and explored a potential mediation of density-dependence by environmental factors. The analyzed data, collected by us over 13 consecutive years (2009–2022), contain information on seven species of long-distance migratory insectivorous passerines measured within eight desert-edge habitats throughout autumn and spring migrations. As predicted, our analyses revealed negative density-dependence regulation of FDRs, consistent across species and migration seasons. Notably, bird density exerted its effect above and beyond the other factors known to influence FDR, such as relative ambient temperature, phenology, temporal progress of stopover, and body mass next to landfall. As expected, FDR increased at higher relative ambient temperatures and with the stopover's progress. In spring, FDR also rose as the season advanced. These findings signify the substantial impact of competition on the refueling performance of migratory passerines during their stopover on an ecological barrier's edge, acting over and above the other environmental factors. The detected importance of competition and its interrelation with other predictors provides an insight into stopover's functioning; environmentally imposed and inescapable interspecific interference is thus a significant limiting factor of FDR, a deleterious relationship potentially remediable by informed habitat restoration and planning.

Original languageEnglish
Article numbere03137
JournalJournal of Avian Biology
Issue number11-12
StatePublished - 1 Nov 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Journal of Avian Biology published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos.


  • competition
  • ecological barrier
  • fuel deposition
  • migration
  • phenology
  • stopover

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology


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