How microtopography affected waterbird habitat selection through bird-human visibility: Inspiration for habitat design.

Microtopography influenced the visibility of waterbirds to human activities, which effected the habitat selection of waterbirds. However, previous studies mainly used topographic data to explore the impact of hydrological conditions or vegetation factors on waterbird habitat selection, but largely ignored the discussion of human interference and were unable to fully explain the rules of waterbird habitat selection. This study focused on storks/cranes and shorebirds living in six waterbird habitats in Yancheng coastal area, China. Waterbird-human visibility was incorporated as one of the anthropogenic activity variables in the species distribution model to simulate and analyze habitat selection probabilities for different waterbird groups. In addition, the significance of visibility as a factor within anthropogenic activities was analyzed across different visual radii. The results showed that: (1) Microtopography-based waterbird-human visibility affected the habitat selection in both groups of waterbirds, ranking as the most influential variable among those related to human activities. When the visible radius was 100 m, storks/cranes were more sensitive to visible disturbance compared to shorebirds. (2) As the visible radius increased, the importance of waterbird-human visibility in habitat selection gradually decreased. At a visible radius of 300 m, waterbird-human visibility had no effect on storks/cranes, which suggested that the effect of microtopography was almost non-existent at this radius. (3) As waterbird-human visibility increased, habitat selection probability of waterbirds decreased, with storks/cranes showing a faster decline compared to shorebirds. (4) By increasing microtopography to reduce waterbird-human visibility, habitat selection probability could increase by up to 10.4 times (from 0.05 to 0.52) in storks/cranes, and 2.3 times (from 0.23 to 0.53) in shorebirds. Therefore, waterbirds exhibited a certain sensitivity to visible anthropogenic disturbance. These findings contributed to a deeper understanding of habitat selection mechanisms of waterbirds and provide a scientific basis for the creation of local waterbird microhabitats.