Reactions to Human Disturbances in an Urban Population of the Swan Goose Anser cygnoides in Heidelberg (SW Germany)
2003
Randler, Christoph
A total of 127 cases of disturbances were recorded, most of them resulting in not-too-serious reactions. An average disturbance affected 25 geese, occurred at 43 m distance to the cause and lasted 31–60 s. Geese feeding prior to the disturbance reacted more strongly than resting ones, and they were more sensitive to disturbances during the hatching and moulting/flightless period. More than fifty percent of the disturbances were caused by dogs — they affected significantly more geese, caused longer durations of disturbances, and probably higher energy costs. There were highly significant positive correlations between a reaction, the duration of a disturbance and the number of geese affected. However, distance to the waterline correlated only with the number of geese affected. Distance to waterline and distance to the source of the disturbance had a high impact on the number of geese affected in a regression model. When disturbances occurred at greater distances, these were more serious, lasted longer and affected more geese. Separate analysis of the dogs demonstrated the influence of dog size (the larger the dog, the greater the disturbance), but not whether it was on a lead. Fleeing into the water was caused by dogs more often than expected. Habituation to an urban environment and predictions for fleeing behaviour are discussed.
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