Nests of the white stork as suitable microsites for the colonisation and establishment of ruderal plants in the agricultural landscape

Abstract

Plants are used by many bird species as structural elements and as lining materials for nests. In building their nests, birds not only use plant stems, but also transport seeds attached to them. This may lead to dispersal of seeds from the parental population into heterogenic environments. In this study, we investigate the role of nests of the white stork as potential microsites for the establishment and growth of seeds contained in nest materials. From 27 white stork nests, we collected 313 specimens from 23 plant species. Numbers of individual specimens and values of plant species richness were significantly lower in nests occupied by storks than in unoccupied nests. The abandonment of nests promotes the succession of some plant species from seed banks contained in the nests, involving plant species different from those cultivated from the nest seed bank. It should be noted here that the specific physical environments of nests constitute the main factor in the development of a pool of specialised plant species in the nests, with the prevalence of ruderal species. These plants usually derive from local ruderal vegetation, which is abundant in agricultural landscapes. Our study showed that large birds created a microhabitat in their nests which was favourable to nest-mediated seed dispersal, as was the incidental accumulation of plant species as a seed bank in the nest. We show that seeds contained in the nests of large birds may germinate and grow, and that eventually fully-grown plants can produce seeds, especially barochorous plant species.