<b>Black-headed gulls (</b><b><i>Chroicocephalus ridibundus</i></b><b>) are more wary of male researchers</b>

The experiment was conducted in December 2022 in Kunming (24°23′–26°22′ N, 102°10′–103°40′ E). Dian Lake, located in the southern side of the main urban area of Kunming City, with a water area of 330 km², attracts thousands of black-headed gulls (<i>Chroicocephalus ridibundus</i>) for overwintering annually. There are several gull-watching spots around Dian Lake, and black-headed gulls are concentrated in the Haigeng Dam and Haigeng Park areas (Feng and Liang, 2020); thus, these two sites were selected to measure the FIDs of black-headed gulls.In this study, we compared the differences in flight initiation distance (FID) of black-headed gulls (<i>Chroicocephalus ridibundus</i>)<b> </b>in Kunming City, southwest China, based on the sex of approaching individuals, as well as the differences in FID of gulls when approached by a boat versus a human on the shore. Results showed that: 1) black-headed gulls had longer FIDs when approached by male researchers than when approached by female researchers; 2) black-headed gulls on the ground had longer FIDs than those on the railing by the lake; 3) adult gulls on the ground had longer FIDs than juvenile gulls on the ground; 4) black-headed gulls had longer FIDs when approached by a boat than when approached by humans on the shore. Our study indicated that black-headed gulls exhibit a greater degree of wariness toward men than women, and compared to humans, boats pose a greater threat to black-headed gulls. To promote the harmonious coexistence of animals and humans in cities, it is important for humans to minimize the disturbance caused by their activities to animals.