Time budget of common cranes (Grus grus) varies between habitats: implications for management

Abstract

Common cranes (Grus grus) of the growing population in Finland form flocks on cultivated fields to forage in the autumn after the breeding season, in preparation for a successful migration. However, human-crane conflicts can arise when cranes cause crop damage, and for management purposes, it is important to prevent such conflicts. To minimize crop losses, one strategy is the creation of artificial feeding fields in high-use areas. Our study area, Söderfjärden, Ostrobothnia, on the west coast of Finland, is the most important staging area for cranes in the country. We compared the time allocation in the most attractive habitats in this area, investigated the changes in flock size during the day, and considered the management implications. Cranes used the two top-rated habitats (barley fields and grasslands) for clearly different purposes: barley fields for feeding and grasslands for resting. Flock size increased from the early morning until the evening when cranes dispersed from the area to roost. This could be a result of a trade-off between food intake and risk-sensitive behaviour and predator avoidance, although at present the predation risk in the area is low. This study highlights the importance to make artificial feeding habitats to fulfil various needs of cranes while minimizing crop loss and potential conflicts with humans. Keywords: common crane, Gruidae, conservation, foraging, habitat selection, vigilance