Population changes in European herons in relation to African climate

We describe population changes for six heron species, which have occurred d uring the past three decades in five areas of southern and central Europe. We seek correlations in the population levels between areas and between spe cies, and we test the relationship between breeding population and climate during the preceding winter in Africa, where some of these herons overwinte r. We conclude that population levels of European herons are influenced by local conditions more than by factors acting on a wide geographic scale, an d that hydrological conditions in sub-Saharan Africa during winter have sig nificant but limited effects on breeding populations of herons in Europe.