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

Abstract

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 iconic bird species, protected across Europe, which, thanks to conservation programs and its ability to utilize croplands for foraging, shows a strongly increasing population trend. This exaggerates the already existing conflicts between crop farmers and cranes spilling over to natural habitats, where foraging by large flocks can lead to land degradation. To date, no studies have evaluated the effects of biopedturbation by cranes in grasslands, despite these habitats provide important feeding grounds for this large bird across its whole range. Here we evaluated the effect of biopedturbation by 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 intact grasslands in two seasons and two years (800 observations). We found that cranes created distinct habitat patches with different species composition compared to undisturbed areas. These early-successional patches that increased the plant diversity and floral resources but decreased the area of intact grasslands. Although crane-disturbed patches could provide forage for livestock early in the season, the forage quality of the vegetation became poor later in the year. Given the strong increase of the global crane population, monitoring the landscape-level extent of the disturbed areas, and developing a complex prevention and mitigation strategy would be important.