Forsyth David M, Hickling Graham J
Department of Entomology and Animal Ecology, P.O. Box 84, Lincoln University, Canterbury, New Zealand Fax: 0064 3 325 3844; e-mail:
Oecologia. 1998 Jan;113(3):377-382. doi: 10.1007/s004420050389.
There is anecdotal evidence that increasing densities of Himalayan tahr (Hemitragus jemlahicus) are associated with declining densities of chamois (Rupicapra rupicapra) in the Southern Alps, New Zealand. To examine this phenomenon, densities of tahr and chamois were measured at 53 sites within their sympatric range in the eastern Southern Alps during 1978-1979. In sites where only one species was present, tahr density was significantly higher than chamois density (P=0.032), probably reflecting species differences in sociality. Chamois density was higher in catchments without tahr than in those with tahr (P=0.012). Similarly, tahr density was significantly higher at sites without chamois than at those with chamois (P=0.033). Sites with both species present (termed sympatric) were significantly larger than those with only chamois or tahr (P<0.001). Following the prohibition of aerial hunting of tahr in 1983, 16 of the 17 sites where tahr and chamois were sympatric during 1978-1979 were recounted during 1991-1996. There was a 6-fold increase in the mean density of tahr between the two counts (P=0.001), whereas chamois density had declined significantly (P=0.006). Chamois persisted at only three sites, two of which had the highest chamois densities in 1978-1979. This is evidence that increasing densities of tahr exclude chamois from all but the `best' habitats. We conclude that intensive aerial hunting of tahr during 1967-1983 reduced tahr densities such that chamois could co-exist with tahr.
有传闻证据表明，在新西兰南阿尔卑斯山，喜马拉雅塔尔羊（喜马拉雅塔尔羊属）密度的增加与岩羚羊（岩羚羊属）密度的下降有关。为了研究这一现象，1978 - 1979年期间，在南阿尔卑斯山东部它们的同域分布范围内的53个地点测量了塔尔羊和岩羚羊的密度。在仅有一种物种存在的地点，塔尔羊的密度显著高于岩羚羊的密度（P = 0.032），这可能反映了物种在社会性方面的差异。没有塔尔羊的集水区的岩羚羊密度高于有塔尔羊的集水区（P = 0.012）。同样，没有岩羚羊的地点的塔尔羊密度显著高于有岩羚羊的地点（P = 0.033）。两种物种都存在的地点（称为同域分布地点）明显大于只有岩羚羊或只有塔尔羊的地点（P < 0.001）。1983年禁止对塔尔羊进行空中捕猎后，在1991 - 1996年期间对1978 - 1979年塔尔羊和岩羚羊同域分布的17个地点中的16个进行了重新计数。两次计数之间塔尔羊的平均密度增加了6倍（P = 0.001），而岩羚羊的密度显著下降（P = 0.006）。岩羚羊仅在三个地点存活，其中两个地点在1978 - 1979年拥有最高的岩羚羊密度。这证明了塔尔羊密度的增加将岩羚羊排除在除“最佳”栖息地之外的所有地方。我们得出结论，1967 - 1983年期间对塔尔羊的密集空中捕猎降低了塔尔羊的密度，从而使岩羚羊能够与塔尔羊共存。
