Abstract:

Quantitative study on time budget and activity rhythm of Saunders's Gull was conducted during different breeding cycle at Yancheng of Jiangsu from 1999 to 2002. Different daily activities during the early breeding cycle showed a clear rhythm, which included foraging accounting for 39.36% of the whole time budget from daily a.m.7:00 to p.m.17:00, maintenance (37.95%), locomotion (9.48%), alert (8.30%), and drinking (5.03%). However, the different daily activities during the late breeding cycle did not show a clear rhythm, which included foraging (42.53%), maintenance (14.21%), locomotion (17.65%), alert (14. 52%) and drinking (10.93%). Time budget of locomotion and alert during the late breeding cycle was significantly longer than during the early breeding cycle; however, time budget of maintenance was significantly shorter. Difference of daily activities rhythm between the early and late breeding cycle was mainly aroused by the change of foraging sites and brooding behavior. Incubation time budget ratio of female to male was 1.24. Daily incubation time budget was accordingly prolonged with the increase of incubation date, and one daily longest incubation time could reach 201 minute.

Key words: Saunders's Gull, Breeding cycle, Time budget, Activity rhythm, Behavior, Yancheng of Jiangsu