Daily Rhythm And Behavioral Time Budget Of Wintering Black-headed Gulls In The Green Lake,Kunming

The Black-headed Gull(Larus ridibundus)is one of the most common mediumsized migratory birds in Eurasia and the eastern coastal areas of North America.In China,the Black-headed Gull is widely distributed in all provinces,breeding in the northeast and northwest regions,and overwintering in the eastern coastal areas and almost all lakes,rivers,and coastal areas south of 32oN.Since the Black-headed Gulls arrived in Kunming city for wintering in 1985,the number of them arriving in Kunming for wintering showed a jumping increase for more than 30 years.The Green Lake has become one of the important habitats of the wintering Black-headed Gulls in Kunming.To understand the daily behavior patterns,behavioral time budget and the adaptation to urban environment of the wintering Black-headed Gulls,and to further explore the relationship between human and gulls,in this paper,with the scan-sampling technique,the daily rhythm and behavioral time budget of the Black-headed Gulls during the wintering period were investigated from November 2017 to February 2018 and November 2018 to February 2019 in the Green Lake,Kunming,Yunnan Province.Some results and conclusions have been drawing out:1.The daily rhythm and behavioral time budget of the wintering Black-headed Gulls in the Green lake were the adaptation to the surrounding environment.The ratio of daytime behavioral time budget of the Black-headed Gulls in the entire wintering period were: foraging(44.01 ± 1.70)%,resting(18.84 ± 0.93)%,maintenance(9.44 ± 1.00)%,alerting(2.45 ± 0.57)%,walking(3.01 ± 0.39)%,swimming(13.77 ± 1.01)%,and flight(8.47 ± 0.68)%.The results indicated that foraging behavior was the most important behavior in the wintering period of the Black-headed Gulls,and it occurred most frequently in various behaviors.Among these behaviors,walking behavior and flight behavior were extremely significant differences in various time during the day(P < 0.01),occurred with obvious daily rhythm,and there was no significant difference in the daily rhythm of other behaviors.Foraging behavior(F = 9.112,P < 0.01)and resting behavior(F = 12.798,P < 0.01)were extremely significant difference between different months while alerting behavior(F = 3.358,P < 0.01)was significantly different in different months,occurred with obvious changes in monthly rhythm,and monthly rhythm of other behaviors were no significant difference.2.The overwintering Black-headed Gulls are mainly replenishing and accumulating energy during the whole wintering period in the Green Lake,the foraging behavior of them has two peaks in the morning and afternoon,while the peaks of resting behavior appeared the noon and afternoon before leaving the urban area,showing an obvious behavioral pattern of "foraging in the morning + resting at noon + foraging in the afternoon." There was an extremely significantly negative correlation between two behaviors of foraging and resting(r =-0.750,P < 0.01);the pattern of misaligned peaks and the trade-off between foraging and resting were critical for the Black-headed Gulls to survive during harsh winters.3.Temperature and moisture are two important factors that affected the behavioral time budget of wintering Black-headed Gulls in the Green Lake.The proportion of foraging behavior increased with the increase of temperature,while the proportion of resting behavior,walking behavior,and flight behavior decreased with the increase of temperature.Partial correlation analysis showed that the effects of temperature and moisture on behaviors of wintering Black-headed Gulls were influenced by each other,and they affect the behavioral time budget through each other.4.The number of wintering Black-headed Gulls and their behavior showed the obvious differences under different human activity conditions.There are more wintering Black-headed Gulls in the waters with more human activities and less wintering Blackheaded Gulls in the waters with fewer human activities.The time spent on foraging behavior,walking behavior,swimming behavior,and flight behavior in the waters with more human activities were higher than waters with fewer human activities.On the contrary,the resting behavior,maintenance behavior,and alerting behavior occurred more frequently in the waters with fewer human activities than the waters with more human activities.The wintering Black-headed Gulls of Kunming showed strong adaptability to human activities,and human activities have a positive influence on the foraging behavior of overwintering Black-headed Gulls in urban areas of Kunming.