Pistorius Pierre A, Follestad Arne, Taylor Frances E
Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway.
Ibis (Lond 1859). 2006 Jan;148(1):114-125. doi: 10.1111/j.1474-919X.2006.00498.x. Epub 2006 Jan 19.
The Norwegian Greylag Goose population has been increasing steadily over the past few decades, causing increasing nuisance in terms of agricultural crop damage. This, in combination with the importance of Greylags as a hunting target, has called for demographic estimates for the population to assist in management decisions. To this end, we analysed long-term mark-recapture data using Cormack-Jolly-Seber models embedded in program MARK to obtain survival estimates for the population. No sex-specific difference, or age effect on survival after juveniles had completed their first migration (3 months of age), was evident. Mean first-year survival was reported as 0.485 and annual survival of older birds as 0.700. On a monthly basis, survival in Greylags during summer and winter was very similar over the study period. A significant linear decline in winter survival from 0.909 to 0.807 was, however, apparent during the study period. Over the second half of the study (1994-2002), summer survival was about 3% lower than in the first half (1986-94) but no linear relationship was evident. We found a significant inverse relationship between Greylag survival during summer and latitudinal distribution in Norway. A similar relationship was evident between survival and annual bag numbers. The changes in adult survival observed in this study are likely to have had a substantial impact on the growth rate of the Norwegian Greylag population.
在过去几十年里，挪威灰雁的数量一直在稳步增长，在农作物受损方面造成的滋扰也日益增加。这一点，再加上灰雁作为狩猎目标的重要性，使得有必要对该种群进行种群统计学估计，以辅助管理决策。为此，我们使用嵌入在MARK程序中的Cormack-Jolly-Seber模型，分析了长期的标记重捕数据，以获得该种群的生存估计值。在幼鸟完成首次迁徙（3个月大）后，未发现性别特异性差异或年龄对生存的影响。据报告，第一年的平均生存率为0.485，年长鸟类的年生存率为0.700。在整个研究期间，夏季和冬季灰雁的月度生存率非常相似。然而，在研究期间，冬季生存率从0.909显著线性下降至0.807。在研究的后半段（1994 - 2002年），夏季生存率比前半段（1986 - 94年）低约3%，但未发现明显的线性关系。我们发现挪威灰雁夏季生存率与纬度分布之间存在显著的负相关关系。在生存率与年度猎获量之间也存在类似的关系。本研究中观察到的成年灰雁生存率变化可能对挪威灰雁种群的增长率产生了重大影响。
