Population and social dynamics changes in ring-tailed lemur troops at Berenty, Madagascar between 1989–1999
Population and social dynamics changes in ring-tailed lemur troops at Berenty, Madagascar between 1989–1999
复制标题
1989-1999 年间马达加斯加贝伦蒂环尾狐猴种群的数量和社会动态变化
作者：
N. Koyama;M. Nakamichi;Shinichiro Ichino;Y. Takahata
在本研究中，我们记录了1989年9月至1999年8月期间马达加斯加贝伦蒂保护区环尾狐猴种群的所有出生、迁入、死亡和迁出。1989年9月，三个部队（C、B和T）居住在14.2公顷的研究区。在10年的时间里，八个部队师，六个驱逐女性，和三个部队接管范围内发生的其他部队和周围的研究区域。因此，1999年8月，同一地区的部队人数增加到6人（CX、C1、C2 A、C2B、T1和T2）。年龄大于1岁的狐猴数量从63只增加到82只，其中204只出生，58只移民，125只死亡和118只移民。在研究期间的204只新生狐猴中，103只死亡，44只迁移到研究区域外，57只留在研究区域内。从纳塔尔部队迁移的狐猴总数为69只（54只雄性和15只雌性）。纳塔尔的男性在3岁左右就离开了他们的部队。非出生男性在服役1至7年后更换部队。存活曲线显示，在2岁至3岁之间，两性的存活率均下降至< 0.5。对于女性，存活率逐渐下降到9岁时< 0.2。另一方面，由于移居国外，无法确定5岁后雄性的存活率。由于一些雄性在6 - 10岁时达到高级，雄性环尾狐猴的黄金年龄被认为是7 - 10岁左右。环尾狐猴本质上是雌性的亲卫动物，因为所有雌性离开纳塔尔部队的案例都是由于部队分裂或强制驱逐。这种社会变化可能是女性之间竞争的结果。所有的部队分裂或驱逐事件都发生在由≥20只狐猴组成的较大部队中，只有少数雌性能够重新加入他们的部队。当雄性加入这样一个雌性群体时，一个新的群体就形成了。虽然数量的增加促进了环尾狐猴种群的发展，但贝伦蒂的环尾狐猴的特征是雌性从原来的种群中频繁迁移。
In the present study, we recorded all births, immigrations, deaths, and emigrations for a population of ring-tailed lemurs at Berenty Reserve, Madagascar, between September 1989 and August 1999. In September 1989, three troops (C, B, and T) inhabited the study area of 14.2 ha. During the 10-year period, eight troop divisions, six evictions of females, and three troop takeovers of ranges by other troops occurred in and around the study area. Consequently, in August 1999, the number of troops in the same area increased to six (CX, C1, C2A, C2B, T1, and T2). The number of lemurs aged >1 year increased from 63 to 82, which resulted from 204 births, 58 immigrations, 125 deaths, and 118 emigrations. Of the 204 newborn lemurs during the study period, 103 died, 44 emigrated outside the study area, and 57 remained within the study area. The total number of lemurs that emigrated from natal troops was 69 (54 males and 15 females). Natal males left their troops around the age of 3. Non-natal males changed troops after a tenure varying from 1 to 7 years. Survival curves showed a fall in survival rates of both sexes to < 0.5 between the ages of 2 and 3. For females, the survival rate gradually decreased to < 0.2 at the age of 9. On the other hand, due to emigration, the survival rate of males could not be determined after the age of 5 yr. Since some males attained high-rank at the age of 6 – 10 yr, the prime age for male ring-tailed lemurs is thought to be around 7 – 10 yr. Ring-tailed lemurs are essentially female philopatric, because all cases of females leaving natal troops resulted from troop divisions or forced evictions. Such social changes may have resulted from competition among females. All cases of troop divisions or evictions occurred in larger troops consisting of ≥20 lemurs, and only a few females could rejoin their troops. When males joined such a female-group, a new troop was formed. Although promoted by an increase in population, frequent emigrations of females from original troops are the characteristics of ring-tailed lemurs at Berenty.