Oldal címe

The Eurasian crane (Grus grus) as ecosystem engineer in grasslands ‒ conservation values, ecosystem services and disservices related to a large iconic bird species

Címlapos tartalom

Large bird species, such as cranes are involved in human-wildlife conflicts as they often forage in croplands. The Eurasian crane (Grus grus) is a large bird species, protected across Europe, which, thanks to conservation programmes and its ability to utilise croplands for foraging, shows a strongly increasing population trend. This exaggerates the existing conflicts between crop farmers and cranes and is spilling over to natural habitats, where foraging by large flocks can lead to land degradation. No studies have evaluated the effects of foraging cranes on grasslands, despite the fact that these habitats provide important feeding grounds for cranes across their whole range. To fill this knowledge gap, we evaluated the ecosystem engineering effect of foraging Eurasian cranes on the vegetation of dry grasslands in Hungary. We used indicators of vegetation naturalness, forage quality, and floral resource provision to evaluate the ecosystem state from multiple aspects. We sampled 100 quadrats in disturbed patches and 100 in undisturbed grasslands in two seasons and 2 years (800 observations). Cranes created distinct vegetation patches with different species composition from undisturbed areas. We identified important trade-offs between the positive and negative effects of the foraging activity of cranes on different structural and functional components of the ecosystems. The crane-disturbed early-successional patches increased plant diversity and floral resources but decreased the area of undisturbed grasslands. Although crane-disturbed patches could provide forage for livestock early in the season, the forage quality became poor later in the year. We highlight the importance of monitoring the landscape-level extent of the disturbed areas.