Living together: Waterbirds distinguish between local fishermen and casual outfits
Changzhang Feng, Wei Liang
Abstract
Increasing global human population and constant exploitation and utilization of natural resources have strongly impacted bird populations worldwide. Thus, it is very important for birds to recognize which activities are threatening and which are not. This ability could accelerate the adaptation of certain species to the changing environment. However, few studies have explored the ability of wild birds to recognize human individuals. This study aimed to investigate the ability of waterbirds to identify local fishermen from outsiders. Specifically, two experiments were conducted in the workplace of fishermen, a tidal flat, where a person was dressed up in a casual outfit and a fisherman outfit, respectively, to measure the flight initiation distances (FIDs, the distance at which a prey starts to flee at the approach of a predator) of waterbirds. The FIDs of eight species of waterbirds were significantly different after seeing the fisherman outfit versus the casual outfit. Compared to the casual outfit, the FIDs of birds to the fishermen outfit were noticeably shorter. Thus, waterbirds are able to distinguish between unknown (threatening) and known (non-threatening) human individuals based on the differences in appearance. Our results are of importance for bird conservation and ecotourism.