Setback Distances as a Conservation Tool in Wildlife-Human Interactions: Testing Their Efficacy for Birds Affected by Vehicles on Open-Coast Sandy Beaches

In some wilderness areas, wildlife encounter vehicles disrupt their behaviour and habitat use. Changing driver behaviour has been proposed where bans on vehicle use are politically unpalatable, but the efficacy of vehicle setbacks and reduced speeds remains largely untested. We characterised bird-vehicle encounters in terms of driver behaviour and the disturbance caused to birds, and tested whether spatial buffers or lower speeds reduced bird escape responses on open beaches. Focal observations showed that: i) most drivers did not create sizeable buffers between their vehicles and birds; ii) bird disturbance was frequent; and iii) predictors of probability of flushing (escape) were setback distance and vehicle type (buses flushed birds at higher rates than cars). Experiments demonstrated that substantial reductions in bird escape responses required buffers to be wide (> 25 m) and vehicle speeds to be slow (< 30 km h-1). Setback distances can reduce impacts on wildlife, provided that they are carefully designed and derived from empirical evidence. No speed or distance combination we tested, however, eliminated bird responses. Thus, while buffers reduce response rates, they are likely to be much less effective than vehicle-free zones (i.e. beach closures), and rely on changes to current driver behaviour.

在部分荒野区域，野生动物与车辆的遭遇会干扰其行为模式与栖息地利用。当车辆使用禁令因政治因素难以推行时，学界已提出通过改变驾驶者行为来缓解该问题，但车辆避让间距与减速行驶的实际效果仍未得到充分验证。我们从驾驶者行为与对鸟类造成的干扰两个维度，对鸟类与车辆的遭遇场景进行了特征分析，并检验了空间缓冲带或更低车速是否能减少开阔海滩上鸟类的逃逸反应。定点观测结果显示：其一，多数驾驶者并未在车辆与鸟类之间留出足够的缓冲间距；其二，鸟类受到的干扰频发；其三，鸟类惊飞（逃逸）概率的预测因子为避让距离与车辆类型——巴士引发鸟类惊飞的比例显著高于轿车。实验结果表明，若要大幅降低鸟类的逃逸反应，需设置宽度大于25米的缓冲带，并将车辆时速控制在30公里每小时以内。只要避让间距经过合理设计且基于实证依据制定，便可降低对野生动物的负面影响。但我们测试的所有车速与间距组合均无法完全消除鸟类的逃逸反应。因此，尽管缓冲带能降低鸟类的反应频率，但其效果远不如无车辆区域（即海滩封闭措施），且依赖于驾驶者现有行为模式的改变。