Evaluating the statistical power of detecting changes in the abundance of seabirds at sea
Evaluating the statistical power of detecting changes in the abundance of seabirds at sea
复制标题
评估检测海上海鸟丰度变化的统计能力
DOI：
10.1111/j.1474-919x.2012.01272.x
复制
发表时间：
2013
期刊：
影响因子：
2.1
通讯作者：
C. Thaxter
中科院分区：
文献类型：
--
作者：
I. Maclean;M. Rehfisch;H. Skov;C. Thaxter
最近，全球海鸟的困境引起了人们的极大关注，因为许多物种数量大幅减少。在英国，法定需要监测海上海鸟，特别是考虑到新的近海区域被指定为保护对象以及大型海上风电场开发计划。然而，海上调查能够在多大程度上检测丰度变化以及改进调查协议的选择却很少受到关注。我们通过海上调查来研究检测数字变化的能力。利用视觉空中海鸟调查计划（覆盖英国水域“第二轮”海上风电场开发区域）收集的数据，我们量化了变异性并描述了计数数据的统计特性。通过生成与真实数据具有相同属性的随机数据集，我们估计了能够检测各种下降（50%、33%、25%、15% 和 10%）的能力，并评估了调查持续时间和频率以及空间规模和鸟类数量变异性的影响。结果表明，英国“第二轮”海上风电场目视空中海鸟调查计划使用的调查设计协议没有提供足够的手段来检测数量变化，即使下降超过 50% 并且有关确定性的假设放宽至 0.8）。能够检测到一致的方向变化的可能性较低的主要原因是海鸟数量在任何给定位置都会波动很大。需要有解释这种精细尺度变异的方法，特别是如果要检测到群体的微小变化。将流体动力学变量纳入趋势分析可能会增加检测变化的能力。未能检测到海鸟数量的变化并不意味着没有发生变化。
There has been considerable recent concern about the plight of seabirds globally, as many species have declined substantially. In the UK there are statutory needs to monitor seabirds at sea, particularly in light of new offshore areas being designated for conservation and plans for major offshore wind farm developments. However, the extent to which at-sea surveys are capable of detecting changes in abundance and options for improving survey protocols have received little attention. We investigate the power of detecting changes in numbers using at-sea surveys. Using data collected as part of a visual aerial seabird survey programme that covered areas of ‘Round 2’ offshore wind farm developments in UK waters, we quantify the variability and characterize the statistical properties of count data. By generating random datasets with the same properties as real data, we estimated the power of being able to detect various declines (50, 33, 25, 15 and 10%) and assessed the effects of survey duration and frequency and of spatial scale and variability in bird numbers. The results indicate that the survey design protocols used for the UK ‘Round 2’ offshore wind farm visual aerial seabird survey programme do not provide adequate means of detecting changes in numbers, even when declines are in excess of 50% and assumptions regarding certainty are relaxed to 0.8). The primary reason why there is a low probability of being able to detect consistent directional changes is that seabird numbers fluctuate greatly at any given location. Means of explaining this fine-scale variability are required, especially if small changes in populations are to be detected. Incorporating hydrodynamic variables into trend analysis might increase the power of detecting changes. Failure to detect changes in seabird numbers should not be taken to mean that no changes are occurring.
影响因子：
5.7
作者：
Votier, Stephen C.;Bearhop, Stuart;Newton, Jason
通讯作者：
Newton, Jason