Picture: Flocks of barnacle geese coming in thousands on a field next to the coast, in central Denmark.
Results from a study conducted on Norway on the effect of scaring geese periodically
Since the mid-20th century, farmers have been scaring geese by using stationary devices - but without much success, as the birds quickly get used to it. Instead of using the devices, it has been more effective to just go out to the birds and clap your hands until they are all gone. However, such method consumed too much time for the farmers.
This research paper is the first study to test the relationship between scaring efforts and geese presence, fleeing response distance to the scarer, and flock sizes.
Each day for a period of 21 days, several fields were assigned a daily scaring dose by a person clapping from 0-10 times throughout the day to scare away entire flocks of geese. The number of geese in the flock was counted each time. The reaction distance of the geese (the distance between the person walking towards the flock and the first goose to take off) is about 10 meters. The geese droppings were also measured to help understand the intensity of the geese's presence over time.
Summary of the results of the study
Active and systematic scaring is an effective tool - scaring five or more times a day is a necessity to reduce goose presence. The effects are more pronounced on the first week, with a 50% reduction in presence, as measured by the droppings of the geese in the field.
Flock size is not reduced by increasing intensity, as they all move as a single herd. It may increase as more geese join from the south, and slowly decline again before the start of the migration period.
Fleeing response distance increases over time, as opposed to what was first assumed. This measures the distance needed between the person and the first goose to take off. A theory states that this happens due to the extra weight of the geese as they're building food reserves, resulting in decreased speed to take off. Another theory is that they recognize the scarer and therefore leave the area quicker, as they understand what it represents.
Systematic scaring over several years will lead to the flocks of geese leaving the areas that are seen as dangerous.
Figure: Cumulative number of droppings (Y-axis) per each scaring frequency applied to the fields (X-axis). As can be seen, a daily scaring frequency of 5 times results in the least geese presence on the fields.