Population recovery of black rhinoceros in north-west Namibia following poaching
Population recovery of black rhinoceros in north-west Namibia following poaching
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DOI：
10.1111/j.1469-1795.2010.00434.x
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发表时间：
2011-08-01
影响因子：
3.4
通讯作者：
du Preez, P.
中科院分区：
文献类型：
--
作者：
Brodie, J. F.;Muntifering, J.;du Preez, P.
减少过度捕捞，无论是非法的还是法律的，往往是一个关键的保护目标。然而，即使可以停止过度开发，由于Allee效应，年龄和性别结构的改变以及动物社会系统的破坏，随后的人口恢复率可能会有很大的变化。此外，了解密度依赖性的影响可能很困难，但对长期管理很重要。在这里，我们调查的动态黑犀牛Diceros双角在纳米比亚的Kunene地区，因为他们从非法狩猎恢复。我们使用多层标记-再捕获模型来检验1992年至2005年的生存率和阶段转换率。存活率估计值范围从小牛的0.793到成年雄性的0.910和成年雌性的0.944。成年雌性的年繁殖率估计为0.315。模型的选择表明，这些重要的利率是时间不变的，这表明Allee效应和瞬态动态并没有对人口动态的重要影响，即使在复苏的早期阶段。1992年至2005年，库内内的非法狩猎停止后，相对人口密度大幅增加。然而，最佳拟合模型在估计存活率或阶段转换率时没有包括相对密度。然后，我们使用标记-再捕获分析生成的生命率来构建矩阵投影模型，以评估总体种群动态。仅女性模型给出的人口增长率估计值为λ = 1.011。两性模型表明，人口增长率可能在0.990至1.012之间。即使没有狩猎或密度依赖，这一人口增长率相对缓慢，可能是由于该地区生产力低下。成年雌虫的生殖价值最高，其存活率的弹性最大。迁移成年雌性将导致创始种群中最快的初始种群增长率，但对源种群的影响最大。
Curtailing overharvest, whether illegal or legal, is often a critical conservation objective. Yet even if overexploitation can be stopped, subsequent rates of population recovery can be highly variable due to Allee effects, alterations to age and sex structure and disruptions of animal social systems. Moreover, understanding the influence of density dependence can be difficult but important for long-term management. Here, we investigate the dynamics of black rhinoceros Diceros bicornis in the Kunene region of Namibia as they recover from illegal hunting. We use multi-strata mark-recapture models to examine survival and stage-transition rates from 1992 to 2005. Survivorship estimates ranged from 0.793 for calves to 0.910 for adult males and 0.944 for adult females. The annual reproductive rate in adult females was estimated at 0.315. Model selection showed that these vital rates were time invariant, suggesting that Allee effects and transient dynamics did not have an important effect upon population dynamics, even in the early stages of recovery. Relative population density increased significantly from 1992 to 2005 once illegal hunting had ceased in Kunene. However, the best-fit models did not include relative density in the estimation of survival or stage-transition rates. We then used the vital rates generated from our mark-recapture analysis to build matrix projection models that assessed overall population dynamics. The female-only model gave a population growth rate estimate of lambda = 1.011. Two-sex models suggest that the growth rate of the population could range from 0.990 to 1.012. The relatively slow growth rate of this population, even without hunting or density dependence, could stem from the low productivity of the region. Adult females had the highest reproductive value and their survival had the highest elasticity among vital rates. Translocating adult females would lead to the fastest initial population growth rate in founder populations but would have the most impact on the source population.