云南省纳帕海自然保护区越冬黑颈鹤的集群特征

Flock of Black-necked Crane Wintering at Napahai Nature Reserve,China

2004年10月-2005年5月,在云南纳帕海自然保护区采用定点扫描法对越冬黑颈鹤(Grus nigricollis)的集群类型和集群大小进行了观察。结果表明黑颈鹤夜间集群夜栖,形成较大的夜栖群,平均群体大小为67.9只(16-157,n=17);按照有无灰鹤加入,又将其分为同种集群和混种集群两种类型,其中同种集群的黑颈鹤数量占整个越冬种群的65.3%。在白昼,黑颈鹤以家庭鹤、集群鹤及特殊群体3种类型活动,家庭鹤和集群鹤的平均大小分别为2.7只(2-4,n=145)和16.1只(3-65,n=1017)。黑颈鹤的集群大小并不稳定,在日内和月份间均有明显变化(P=0.000<0.05)。在越冬期,最大集群形成于12月,其次为11月和1月;在日内,早上8时集群最大,随后减小并保持相对稳定,18时黑颈鹤开始向夜栖地靠拢,使得集群再次开始增大。随后观察中还发现,黑颈鹤的家庭解体过程开始于3月底,当幼鹤被成鹤驱逐离群后,逐渐加入集群鹤活动,从而使得家庭鹤和集群鹤的大小和组成发生改变。黑颈鹤的集群大小和组成受自身状况、种内关系、天气、食物等多种因素的共同影响,随时间和季节变动而发生变化,是对自身、种群和环境条件变化的综合反映。

From October 2004 to May 2005, flock size and composition of wintering black-necked cranes （Grus nigricollis） were studied using spot scanning technique at Napahai Nature Reserve in Yunnan province. At night, the mean wintering population size was 67.9 （16-157, n=17）. Composed by common crane （Grus grus） or not, roost cranes were divided into sing-species flock and mixed-species flock. The numbers of crane in sing-species flock were 65.3% of total black-necked cranes. In the day, feeding flocks were classified into three types： family group comprised of breeding pair and their offspring ranging between two to four; sub-adult flock composed mainly by sub-adults ranging between three to 65 with an average size of 16.1（n=1017）; special flock composed by single cranes. Black-necked crane flocks were affected by season, temperature, breeding status, food abundance and availability, and their sizes changed significantly in daytime or between different months （P=-0.000〈0.05）. After family breakup happened in late March, Juveniles were drove away by their parents and then they got together to join the sub-adult flocks.