Groping in the fog: Soaring migrants exhibit wider scatter in flight directions and respond differently to wind under low visibility conditions

Atmospheric conditions are known to affect flight propensity, behaviour during flight, and migration route in birds. Yet, the effects of fog have only rarely been studied although they could disrupt orientation and hamper flight. Fog could limit the visibility of migrating birds such that they might not be able to detect landmarks that guide them during their journey. Soaring migrants modulate their flight speed and direction in relation to the wind vector to optimise the cost of transport. Consequently, landmark-based orientation, as well as adjustments of flight speed and direction in relation to wind conditions, could be jeopardised when flying in fog. Using a radar system operated in a migration bottleneck (Strait of Messina, Italy), we studied the behaviour of soaring birds under variable wind and fog conditions over two consecutive springs (2016 and 2017), discovering that migrating birds exhibited a wider scatter of flight directions and responded differently to wind under fog co...

众所周知，大气条件会影响鸟类的飞行倾向、飞行行为以及迁徙路线。然而，尽管雾可能干扰鸟类的定向能力并阻碍飞行，但相关研究却极少涉及雾的影响。雾会降低迁徙鸟类的可见度，使其无法识别旅途中用于导航的地标。翱翔性迁徙鸟类会根据风矢量调整飞行速度与方向，以优化飞行运输成本。因此，当鸟类在雾中飞行时，基于地标的定向能力以及根据风况调整飞行速度与方向的行为均可能受到损害。本研究借助部署于迁徙瓶颈区域——意大利墨西拿海峡（Strait of Messina）——的雷达系统，在连续两个春季（2016年与2017年）中，针对不同风况与雾情条件下的翱翔性鸟类行为展开研究，发现迁徙鸟类的飞行方向散布范围更广，且在雾天环境下对风的响应模式存在差异，相关研究内容暂未完整呈现。