关键词: 鄱阳湖, 野鸭, 时间分配, 行为节律, 取食策略

Abstract: From October 2019 to January 2020 and October 2020 to January 2021, the behaviors of six wild duck species in Poyang Lake were studied using scan-sampling technique and focal sampling method. The results showed that foraging, resting, grooming, and locomotion were the most frequent behaviors. The proportion of time spent foraging compared with resting was significantly higher (P<0.01) in the Mallard (Anas platyrhynchos), Northern Pintail (Anas acuta), and Ruddy Shelduck (Tadorna ferruginea). The behavioral patterns of these three species were more foraging and less resting. In the Green-winged Teal (Anas crecca) and Eurasian Wigeon (Mareca penelope), the proportion of time spent on resting was significantly higher than that of foraging (P<0.01). The behavioral patterns of these two wild ducks were more resting and less foraging. The Eastern Spot-billed Duck (Anas zonorhyncha) showed no significant difference in the proportion of time spent on foraging to resting (P>0.05), indicating that foraging and resting behavioral patterns were of equal importance for this species. Body size of the six species was not significantly related to the proportion of time spent on foraging (P>0.05) or resting (P>0.05). Time budget was mainly determined by their behavioral patterns. The main foraging method of the Ruddy Shelduck was head and head-neck immersion in water. The other five species used head-neck immersion in water, which may be because their main food supply is under water. The differences in length of heads and necks among the six species resulted in spatial niche separation that decreased their interspecific competition. There was a significant negative correlation between diversity index of foraging patterns and the proportion of locomotion behaviors (r=-0.609, P<0.05) and a positive correlation between the diversity index of foraging patterns and the proportion time spent on foraging (r=0.936, P<0.01). The results showed that wild ducks with more diverse foraging patterns did not need to change their foraging sites frequently, thus reducing the time spent on moving to save energy. The weight of the Green-winged Teal, Eastern Spot-billed Duck, Mallard and Northern Pintail was significantly positively correlated with the duration of head-neck feeding (r=0.999, P<0.01), while was significantly negatively correlated with foraging frequency (r=-1.000, P<0.01). These results indicate that the six duck species have substantial differences in behavioral patterns and that foraging strategies are affected by body size of wild ducks, in that larger ducks adopt the strategy of increasing the feeding duration and smaller ducks adopt the strategy of increasing the frequency of foraging.

Key words: Poyang Lake, wild duck, time budget, behavioral rhythm, foraging strategy.