性别和温度对中华秋沙鸭越冬行为的影响

The effects of gender and temperature on the wintering behavior of Chinese merganser

2011年11月至2012年3月,在江西婺源采用瞬时扫描法探讨性别和温度对中华秋沙鸭行为的影响。中华秋沙鸭越冬期的主要行为是取食、休息、游泳和修整。时间分配方面,雌雄中华秋沙鸭仅社会行为[雌:(2.13±1.40)%和雄:(3.24±1.55)%]存在显著性差异(t=-2.258,df=34,P<0.05),其他行为差异不显著(P>0.05)。原因有:(1)非繁殖期雌雄中华秋沙鸭主要任务均为生存;(2)雌雄个体大小差异不大,对能量的需求量相似。日活动节律方面,雌雄的取食和休息行为均存在显著的节律性变化,分别为雌:取食(F(10,165)=5.19,P<0.05)、休息(F(10,165)=2.56,P<0.05)和雄:取食(F(10,165)=7.55,P<0.05)、休息(F(10,165)=3.48,P<0.05),其他行为节律均不显著(P>0.05)。温度对中华秋沙鸭越冬行为的影响较大,时间分配方面,在<10℃月份环境下,取食(t=-2.166,df=16,P<0.05)行为显著高于>10℃月份,而游泳(t=5.096,df=16,P<0.05)行为则相反,其他行为差异不显著(P>0.05)。这一结果表明,平均温度降低时,中华秋沙鸭需要摄取更多的食物以补充寒冷天气能量的消耗,并减少游泳行为降低耗能。日活动节律方面,>10℃月份中华秋沙鸭日活动节律,仅警戒(F(10,77)=1.96,P<0.05)行为存在显著的节律性变化,其他行为的节律性变化不显著(P>0.05)。<10℃月份中华秋沙鸭取食(F(10,86)=5.93,P<0.05)和休息(F(10,86)=3.42,P<0.05)行为存在显著的节律性变化,其他行为的节律性变化不显著(P>0.05)。研究结果表明,温度可以改变中华秋沙鸭的日活动节律,低温使中华秋沙鸭在夜间消耗较多能量,因此中华秋沙鸭在上午花更多的时间取食来补充能量。休息行为在>10℃月份,中午和傍晚均有一个小的高峰,而在<10℃月份从11:00开始(除13:00—13:59)均保持较高的水平。中华秋沙鸭采取这种对策,可能是<10℃月份,晚上和下午温度较低,为了减少消耗,从下午就开始增加休息行为。低温条件下,中华秋沙鸭增加修整和休息行为,这一结果支持"鸟类在低温环境下通过减少行为活动以降低能量消耗和热量损失"这一观点。

Behavioral rhythms and time budgets are influenced by a number of factors, including temperature, weather, and gender. Animals often adopt different survival strategies in different environments and knowledge of these strategies can benefit the conservation and management of a species. The Chinese merganser （Mergus squamatus） is listed as an endangered species by the International Union for Conservation of Nature. Given the poor status of the species, it is important to understand the factors affecting their survival. To address this, we evaluated the effects of temperature and gender on survival strategies during the wintering period. We observed the behaviors of Chinese Merganser in WuyuanCounty, Jiangxi Province, China, during the wintering season between 13 November 2011 and 13 March 2012. We documented the behavior of individual birds using an instantaneous scanning sampling method. The main behaviors included feeding, resting, swimming, and maintenance. We used an independent sample t-test to analyze for differences in the behavioral time budget between male and females. There was a significant difference between the sexes in social behavior （ P〈0.05 ）, but not other behaviors （P〉0.05）. This is because ： （ 1 ） both males and females are focused on maintaining adequate energy supply to survive during the non-breeding period and （2） there is little difference in the body size of males and females. We observed a clear rhythm in feeding and resting behaviors of both males and females （ one-way ANOVA, P〈 0.05 ）, but not for the remaining behaviors （P 〉 0.05 ）. The air temperature had a significant influence on wintering behavior in the Chinese merganser. The time spent feeding was significantly shorter in months where the average temperature was 〈10℃ month compared to months when the average temperature was 〉10℃ （P〈0.05）. In contrast, the reverse was true for swimming behavior （ P 〉 0.05 ）. Thus, our data suggest that Chinese mergansers minimize energy consumption in cold weather by decreasing activity levels, a strategy to cope with decreased food intake. We observed differences in daily behavioral rhythms between months and behavior types. In the months in which the average temperature was 〉10℃ we observed a rhythm in vigilance behavior （P〈0.05）, but not the remaining behaviors （P〉0.05）. In months in which the average temperature was 〉10℃ we observed a rhythm in feeding and resting behaviors （P〈0.05）, but not in the remaining behavior types （P〉0.05）. Thus, our results suggest that changes in temperature are associated with changes in the daily behavioral rhythms of Chinese mergansers. Low temperatures likely increase energy expenditure during the night, resulting in individuals dedicating more time to feeding in the morning to supplement energy. In 〉 10℃ months, there were two minor peaks in resting behavior： at midday and in the evening. However, in 〈10℃ months the frequency of resting behaviors remained high between 11：00 and 18：00 （except 13：00-13：59）. We hypothesize that the Chinese merganser adopted this strategy because the temperatures were low in the afternoon and evening in 〈10℃ months, resulting inthat this species reduces activity levels to decrease energy consumption and heat loss in lowtemperature environments.