Open access publications in the SLU publication database

Many large grazing bird species (i.e., cranes, geese and swans) have increased tremendously in numbers throughout Europe and North America. When migrating, these species normally aggregate in large numbers at staging sites along the flyways. The staging sites are often located in agricultural landscapes where suitable wetland night roosts are available. When aggregating, the birds generally refuel by foraging at arable land and so causing harvest losses and conflicts between conservation and agricultural interests. Knowledge of the space use and foraging behaviour of large grazing birds is essential to inform management where and when crop damage risk is apparent and how to allocate management measures to alleviate crop damage and associated conflicts between human interests.

The aim of this review is to synthesize knowledge about the factors affecting foraging decisions of large grazing birds and how this knowledge can be used to improve management practices. I focus on species in the genera cranes, swans and geese on the northern hemisphere and particularly species that are increasing in numbers. By reviewing the existing literature, I found that factors such as food availability and quality, distance to roost site, crop type, field size, interspecific competition and disturbance risk generally influence field use by large grazing birds and thus damage risk across the agricultural landscape. These factors can thereby potentially also inform managers where and when to allocate and priorities crop damage preventive measures. Based on these findings, I recommend a “push and pull” strategy where undisturbed diversionary fields with high food availability in the vicinity of the roost sites can function as a “pull” component to attract birds, in combination with scaring and occasionally hunting as a “push” component to steer birds from damage-prone crops. However, many of the large grazing bird species are steadily increasing in numbers and a “push and pull” strategy under such conditions would likely demand also steadily increasing management efforts. For such conditions an adaptive flyway management plan, as implemented for the Svalbard population of pink-footed geese, is to recommend. To mitigate conflicts between conservation and agriculture in such a flyway management plan, ecological knowledge is needed, but also participatory involvement of stakeholders and international collaboration.