鄱阳湖围垦区藕塘越冬白鹤的时间分配与行为节律

2016年12月—2017年3月,采用瞬时扫描法研究了鄱阳湖围垦区藕塘生境中白鹤Grus leucogeranus越冬期的行为,共扫描2560次,23219只次,包括18031只次成鹤和5188只次幼鹤。结果表明,觅食(41.78%)、警戒(25.02%)、修整(15.00%)和休息(10.84%)是白鹤越冬期的主要行为。与自然生境相比,藕塘生境中白鹤主要采取多休息和修整的策略来节省能量支出。成鹤的觅食行为(35.29%)显著低于幼鹤(62.42%)(F_(1,12)=45.977,P0.01),警戒行为(28.66%)则显著高于幼鹤(10.26%)(F_(1,12)=38.975,P0.01)。家庭群成鹤觅食行为(43.96%)极显著高于非家庭群成鹤(27.04%)(F_(1,12)=60.169,P0.01)。家庭群成鹤需要喂食幼鹤,它们花费更多的时间觅食弥补能量的消耗。行为节律上,白鹤各时段觅食行为占总行为的比例均较高,11:00—11:59出现明显高峰,占总行为的48.64%。警戒行为无明显的低谷和高峰。成鹤在各时段的觅食行为比例均明显低于幼鹤,成鹤和幼鹤的觅食曲线变化趋势相似,即觅食比例的升高和降低比较同步。成鹤在各时段的警戒行为和修整行为比例均明显高于幼鹤,成幼鹤的休息行为比例在各时段差别不大,均在14:00—14:59有个明显的高峰。家庭群成鹤的觅食行为比例几乎在各时段均明显高于非家庭群,家庭群成鹤的修整行为和休息行为在大部分时段均低于非家庭群成鹤。因此家庭群成鹤采取多取食,少休息和修整的策略提高自身的适合度,同时保证对后代的抚育。

Study on time budgets and behavioral rhythm of wintering Siberian Cranes in a lotus pond reclamation area in Poyang Lake

Poyang Lake, Jiangxi Province, is the largest lake in China. Many waterbirds inhabit its wetlands, including endangered species such as the Siberian Crane (Grus leucogeranus), of which 95% of known individuals occur in the area. This species is currently listed in the First Category of National Key Protected Wildlife Species in China and among the critically endangered, according to the IUCN; its global population numbers 3500-4000 individuals. Many cranes once foraged in Poyang Lake''s natural habitat during winter, but an increasing number have begun foraging in adjacent artificial wetlands, such as rice paddies and lotus ponds. Since the winter of 2012, less than 100 cranes had been foraging in the Wuxing lotus pond reclamation area, but by the winter of 2016, this number had surged to more than 1,000 individuals. With no information available on how long it took these cranes to adapt to this artificial habitat, what their time budget and behavior rhythms within it were, and what factors affected their wintering behavior. Therefore, from December 2016 to March 2017, instantaneous scan-sampling methods were used in-to our knowledge-the first research of its type in Chinese artificial wetlands on the wintering behavior of Siberian Cranes in a lotus pond reclamation habitat in Poyang Lake. A total 2560 times and 23219 individual-time (18031 individual-time for adults and 5188 individual-time for subadults) were scanned. Seven behavioral activities were recognized:foraging, resting, grooming, vigilance, social, flying, and locomotion. Major behaviors included foraging (41.78%), vigilance (25.02%), grooming (15.00%), and resting (10.84%). Siberian Cranes in lotus pond habitats conserved energy by spending more time resting and grooming. Adult vigilance (F_1,12=38.975, P < 0.01) was significantly greater than subadult vigilance, while adult foraging (F_1,12=45.977, P < 0.01) was significantly less than subadult foraging. Foraging behaviors of adults in family groups were significantly higher than those of adults in non-family groups were, with more time required for foraging to offset the energy consumption of subadult feeding. Cranes maintained high foraging frequencies in each period, with peaks occurring between 11:00 and 11:59 (about 48.64% of the total behavior) in the morning. There were no obvious peaks or troughs in timing spent on vigilance behaviors, with the proportion of adults foraging, lower than that of subadults during each time period, and with the proportion of adults and subadults foraging increasing or decreasing at similar times. During each time period, the proportion of adults performing vigilance or grooming behaviors was greater than that of subadults. No obvious differences were apparent in the timing of adult and subadult resting behaviors, with both peaking between 14:00 and 14:59. During each time period, the proportion of adults foraging in family groups was almost always higher than that of adults in non-family groups. During most time periods, the proportion of individuals grooming and resting in family groups was usually lower than that of adults in non-family groups. Adults in family groups spent more time feeding than they did on resting or grooming behaviors, improving overall fitness, and ensuring nurture.