Foraging of White StorkCiconia ciconiain Forests – The Heritage of an Ancient Behaviour?

Abstract

The white stork Ciconia ciconia is a typical open-area species, foraging mainly in farmland and wetland areas. The main aim of this paper was to describe the foraging ecology of white storks inside un-typical habitat, i.e. forests in Poland. Data on white stork feeding in forests were based on responses to questionnaires distributed to several national mailing lists with a total of 1700 (16% subscribers) and via emails to naturalists (mainly to white stork researchers). In total 63 observations, from the years 2000–2015, were collected, mainly from eastern Poland. In all cases, only a single adult individual was recorded inside the forest, with a mean (±SD) distance to the forest edge of 50 ± 102 m (n = 597) and 1315 ± 1015 m (n = 63) to the nearest white stork nest. Birds foraging inside forests were recorded from late May to mid-August, but the greatest numbers were seen during June. The main prey was a lizard, the slow-worm Anguis fragilis, with a maximum of 10 individuals collected by a stork during one foraging session. We discuss the origin of the observed foraging behaviour, noting that the species is flexible and opportunistic in terms of consumed food. The observed foraging is probably similar to the original behaviour of the species within primeval forest, although food opportunism helps the white stork to use new foraging areas, for example landfills.