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标题：Population decline in the Delta caribou herd with reference to other Alaskan herds
其他标题：Population decline in the Delta caribou herd with reference to other Alaskan herds
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作者：Patrick Valkenburg et al.
期刊名称：Rangifer
印刷版ISSN：1890-6729
出版年度：1996
卷号：16
期号：4
页码：53-62
DOI：10.7557/2.16.4.1221
语种：English
出版社：Swedish University of Agricultural Sciences
摘要：After growing continuously for nearly 15 years, the Delta caribou herd began to decline in 1989. Most other Interior Alaskan herds also began declining. In the Delta herd, and in other herds, the declines were caused primarily by high summer mortality of calves and increased natural mortality of adult females. Other minor causes included increased winter mortality of calves, and reduced parturition rates of 3-year-old and older females. The decline in the Delta herd also coincided with increased wolf (Canis lupus) numbers, winters with deeper than normal snow, and warm summers. Mean body weight of annual samples of 10-month-old female calves was consistently low during the decline. Except in some of the smallest Interior Alaskan herds, we conclude that evidence for population regulation in Alaskan caribou is weak, and that herds are likely to fluctuate within a wide range of densities due to complex interactions of predation and weather. Unless wolf numbers are influenced by man, the size of a caribou herd in a given year is likely to be largely a function of its size during the previous population low and the number of years of favorable weather in the interim.
关键词：Population Ecology; Caribou; Alaska;caribou; rainfall; Rangifer; snow; temperature; weather; wolves; Delta herd; population decline; Alaska