Tolerance Distances Of Common Birds To Human Disturbance In Urban Areas

Urbanization has led to habitat fragmentation and human disturbance,affecting the wildlife living in cities.With the expansion of human activities,the increasing human disturbances in cities has become one of the main threats to the survival of birds.Investigating tolerance distance of common birds to human disturbances in urban areas can help to understand how they behaviorally adapt to the increasing urbanization that has significant impacts on wildlife.From November 2016 to May 2017,we measured alert distance,flush distance,buffer distance and safety distance of common birds in three sites with different degrees of urbanization in Hefei,China.Human disturbances and other environmental variables were also quantified.General linear model was used to test effects of environmental factors on tolerance distances of six species with large sample size.Pearson correlation analysis was used to test correlations among the four distances of each species.The main results are as follows:1.Results indicated that tolerance distances varied among species;oriental turtle dove has the longest tolerance distances,followed by spotted dove,common magpie,common blackbird,azure-winged magpie,Eurasian tree sparrow.There was significant difference in the tolerance distances of six selected birds under different human disturbances.Tolerance distances were negatively associated with human disturbance.This showed that urban birds can adjust tolerance distances to adapt to human disturbance,it has adaption to human disturbance to some extent.2.The tolerance distances of birds were affected by the chosen environmental factors.Alert distance and flush distance was longer in larger groups.Alert distance,flush distance and safety distance were shorter when birds were closer to refuges.Birds on the ground appeared to be less tolerant than those in brush or trees.3.There were positive correlations among the four measured tolerance distances.The greater the alert distance,the earlier the prey found the predator and enter a state of alert but do not flee immediately.Prior to its flight,the prey would have a long time to weigh the cost of flight or staying in place.The risk of predation is reassessed when the prey chooses to fly or run away.Birds with longer alert distance and flush distance are less tolerant to human proximity,therefore,they choose to escape to further place to ensure covertness,showing longer safety distance.This study showed that urban birds can modify their tolerance distances to adapt to intensive human disturbance in cities.According to our findings,we made suggestions on the management and conservation of common birds in the context of urbanization:In the planning and construction of urban parks,we should try to avoid setting places for human activities in areas where bird activities are more frequent,and to plant various trees and shrubs so as to provide safe and reliable habitats for birds.In addition,in the process of urban construction,the tolerance distances of birds can be used as a reference index,on the basis of which the scope of protection can be divided in a targeted manner,minimizing the adverse impact of human disturbance.Continue to increase awareness of bird protection.Differences in biological characteristics of different birds can be used as the basis for urban bird protection strategies,which has more practical significance for promoting the management and protection of wildlife in cities.