Every year the Eurasian crane travel from northern Africa to northern Europe and Asia. On their migration route they need to rest and often choose places around shallow lakes in agriculture landscapes. During their time in these resting sites the cranes forage in agriculture fields surrounding the lakes, which often cause crop-damage and thereof also financial loses. The last 30 years the population has increased radically, resulting in more extensive crop-damage. This study was set out to gain a better understanding how these migrating cranes choose sites to forage, based on four environment factors: roads, water, buildings, trees and shrub. A study-area in north of Lake Tåkern was selected and during six days in the spring all the cranes in the area were counted and marked on a map. The results showed that the factors affected the occurrence of cranes in the fields. They wanted to be close to shallow water and keep a distance to buildings, roads, trees and shrub. The cranes often spend the night in shallow water and search for food in the area close by to not lose too much energy, which probably was the main reason for the birds to stay close to the water. The distance to buildings and roads suggests that the cranes want to avoid interference from humans and the distance to trees and shrub that they want to have a good awareness of their surroundings. Through this understanding, areas with higher risk to attract groups of cranes can more easily be identified.

Wetland species are declining and efforts are being made to protect wetlands and their biodiversity. In Europe, these efforts could be hampered by the recent rise in the Western European Common crane (Grus grus) population. Increasing anecdotal evidence has raised concerns that this population increase has led to an increase in crane predation on other bird species’ eggs and chicks. This study aims to investigate, weather cranes are a potential threat to other bird species by predating on eggs and chicks, and ultimately biodiversity. Proxies, like habitat selection and time devoted to foraging in wetlands, were used to investigate risk of crane predation. Habitat selection and time devotion were studied using location data derived from 13 GPS-tagged Common cranes during May and June in 2017 to 2019. Observational foraging data was collected in the protected wetland Kvismaren, Sweden in June 2019, including adult non-breeding cranes only. During daytime, the three habitats with highest mean relative probability of presence within a 95% confidence interval for cranes are open wetland (0.87, CI: 0.86-0.89), followed by inland water (0.60, CI: 0.56-0.63) and arable land (0.55, CI: 0.52-0.59). The proportion of time cranes spend in wetlands is 0.39 in May and 0.28 in June. Cranes spend a proportional majority of their time (0.69) on foraging behavior compared to other activities they perform in wetlands. Since every encounter with a chick or egg can end in predation and cranes spend most of their time foraging in wetlands a population increase in cranes could have severe impact on bird species. Future research should take into account crane diet, which categories of cranes (e.g., non-breeding versus breeding) are most likely to predate on eggs and chicks and the negative impact on bird populations in relation to crane numbers to fill in the major research gap in this field. Lastly, future studies should evaluate how an increasing crane population also could impact the abundances of other wetland species such as, rodents, amphibians, fish and invertebrates.