Avian escape responses to observers wearing clothing of different colors: A comparison of urban and rural populations

Abstract

Behavioral plasticity is a key factor facilitating the coexistence of humans and other species in a rapidly urbanizing world. An animal’s anti-predation ability is usually estimated by measuring its flight initiation distance (FID). FIDs in birds are affected by multiple factors including the color of the observer’s clothing. The species confidence hypothesis argues that birds are attracted to colors which are the same as or similar to that of their own feathers and repelled by dissimilar colors. So far, there have been no studies on urban vs. rural differences in avian FIDs in response to different colored clothing. In this study, avian escape responses to observers wearing clothing of different colors with red (a bright color), black (dark color contrast), white (bright color contrast) and dark green (a concealment color) in urban (tropical Haikou city) and rural (Dongzhaigang Nature Reserve) populations were examined. Our results showed that urban avian FIDs were significantly shorter than rural avian FIDs. The colors of the observers’ clothing did not have a significant impact on urban avian FIDs. However, rural birds had significantly longer FIDs for observers in red than the other three colors, which impacted them negligibly. To our knowledge, this is the first study to report urban vs. rural differences in avian responses to the colors of observers’ clothing.