Translated from the Dutch SOVON ornithologists:
Friday, March 20th, 2015
About various migratory birds including the purple heron and the sedge warbler it was already known: if there is enough rainfall in the autumn in their wintering grounds in West Africa, it increases the likelihood that they will survive the winter.
An analysis of reed warblers captured in the Netherlands shows the same effect. How many reed warblers return to the Netherlands therefore depends in part on the amount of precipitation that falls in West Africa. This is reflected in the Breeding Birds Report 2013 published today by SOVON.