Journal of Ornithology

, Volume 155, Issue 4, pp 905–917 | Cite as

Rainfall on wintering grounds affects population change in many species of Afro-Palaearctic migrants

  • Nancy OckendonEmail author
  • Alison Johnston
  • Stephen R. Baillie
Original Article


Survival and population growth rates in several species of Afro-Palaearctic migrant have been shown to correlate with rainfall regimes and/or vegetation level on their African wintering grounds, implying that seasonal food resources may contribute to population limitation. Here we explore the generality of this relationship across 16 migrant species breeding in England by investigating the proportion of variability in annual population change that is explained by the impact of environmental variables on wintering and staging grounds over 25- and 40-year time periods. In the 40-year time-series, rainfall in the arid Sahel region of West Africa had the strongest and most consistent effects on migrant populations, positively influencing the population growth rate in six of nine species which winter in this area and in three of seven species that use the region during their migratory passage but which over-winter further south. The effects of precipitation in other regions of Africa and satellite-derived measures of vegetation quality in all regions were weaker and less consistent in direction. Over the 25-year period for which data on both rainfall and vegetation were available, 12 of the 16 study species showed significant weather effects; the mean deviance explained by environmental variables among these 12 species was 32 %, increasing to 41 % when density-dependence was added to the models. For the 40-year time period, 11 species showed significant effects of rainfall, with the mean deviance explained by environmental variables of 14 % (23 % including density-dependence). Our results demonstrate that in many long-distance migrant species, precipitation in the Sahel is a significant driver of changes in abundance at the large-scale population level.


Migrant Palaearctic Precipitation Population NDVI Wintering grounds 


Niederschlag im Überwinterungsgebiet beeinflusst Populationsveränderungen vieler afro-paläarktischer Zugvogelarten

Es ist gezeigt worden, dass Überlebens- und Populationswachstumsraten mehrerer afro-paläarktischer Zugvogelarten mit Niederschlags- oder Vegetationslevel in ihren afrikanischen Überwinterungsgebieten zusammenhängen, was darauf hindeutet, dass saisonale Nahrungsressourcen das Populationswachstum begrenzen können. Hier untersuchen wir die Allgemeingültigkeit dieser Beziehung für 16 in England brütende Zugvogelarten, indem wir den Anteil der Variabilität von jährlichen Populationsveränderungen untersuchen, der mit Hilfe von Umweltvariablen in Überwinterungs- und Rastgebieten über Zeiträume von 25 und 40 Jahren erklärt wird. Der Niederschlag in der ariden Sahelregion in Westafrika zeigte die stärksten und beständigsten Effekte auf Zugvogelpopulationen – bei 6 von 9 Arten, die in dieser Region überwintern, sowie bei 3 von 7 Arten, welche die Region auf dem Durchzug nutzen, aber weiter südlich überwintern, hatte er einen positiven Einfluss auf die Populationswachstumsrate über 40 Jahre. Die Effekte von Niederschlägen in anderen afrikanischen Regionen sowie die Effekte von Maßen der Vegetationsqualität, die von Satellitendaten abgeleitet worden waren, in allen anderen Regionen waren schwächer und wirkten nicht in eine bestimmte Richtung. Für den Zeitraum von 25 Jahren, für den Daten sowohl zum Regenfall als auch zur Vegetation vorliegen, zeigten sich bei 12 der 16 untersuchten Arten signifikante Wettereffekte, und die mittlere Abweichung, die bei diesen zwölf Arten mit Umweltvariablen erklärt werden konnte, betrug 32 %. Sie stieg auf 41 %, wenn Dichteabhängigkeit in den Modellen berücksichtigt wurde. Für den Zeitraum von 40 Jahren hatte der Niederschlag bei 11 Arten signifikante Effekte und erklärte eine mittlere Abweichung von 14 % (23 % einschließlich Dichteabhängigkeit). Wir zeigen, dass bei vielen Arten von Langstreckenziehern der Niederschlag in der Sahelzone einen signifikanten Einfluss auf Veränderungen der Abundanz auf großräumigem Populationsniveau hat.



The CBC was funded by the Joint Nature Conservation Committee (JNCC) on behalf of English Nature, Scottish Natural Heritage, Countryside Council for Wales and the Environment and Heritage Service in Northern Ireland, whilst the BBS is jointly funded by the BTO, JNCC and the Royal Society for the Protection for Birds. We would like to thank Jacquie Clark for help extracting ringing recoveries, Chris Hewson for advice about wintering areas and Michael Schaub and Rob Robinson for comments on the manuscript.

Supplementary material

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Supplementary material 6 (PDF 125 kb)


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Copyright information

© Dt. Ornithologen-Gesellschaft e.V. 2014

Authors and Affiliations

  • Nancy Ockendon
    • 1
    Email author
  • Alison Johnston
    • 1
  • Stephen R. Baillie
    • 1
  1. 1.British Trust for OrnithologyNorfolkUK

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