1950年秋天,大卫和伊丽莎白·拉克偶然发现了昆虫和鸟类的大量迁徙,它们飞过布贾鲁埃洛的比利牛斯山口,从法国到西班牙,后来描述的景象结合了宏伟和新奇。在此期间,土地利用和气候发生了许多变化,提出了这种移民现象的现状问题。此外,由于缺乏定量数据,无法深入了解这种大规模昆虫迁徙的生态影响以及可能影响其的因素。为了解决这个问题,我们在4年的秋季重新访问了该地点,并系统地监测了昼夜昆虫迁徙的丰度和物种组成。我们估计每年平均有1710万天飞昆虫从五个订单中迁移(双翅目,膜翅目,半翅目,鳞翅目和Odonata)向南移动,观察到与温度升高相关的向南“大规模迁移”事件,逆风的存在,阳光,低风速和低降雨量。双翅目在迁徙组合中占主导地位,每年的数字变化超过四倍。这个单一地点的数字暗示,每年可能有数十亿只昆虫穿越整个比利牛斯山脉,我们强调这条路线对季节性昆虫移民的重要性。
In autumn 1950 David and Elizabeth Lack chanced upon a huge migration of insects and birds flying through the Pyrenean Pass of Bujaruelo, from France into Spain, later describing the spectacle as combining both grandeur and novelty. The intervening years have seen many changes to land use and climate, posing the question as to the current status of this migratory phenomenon. In addition, a lack of quantitative data has prevented insights into the ecological impact of this mass insect migration and the factors that may influence it. To address this, we revisited the site in autumn over a 4 year period and systematically monitored abundance and species composition of diurnal insect migrants. We estimate an annual mean of 17.1 million day-flying insect migrants from five orders (Diptera, Hymenoptera, Hemiptera, Lepidoptera and Odonata) moving south, with observations of southward \'mass migration\' events associated with warmer temperatures, the presence of a headwind, sunlight, low windspeed and low rainfall. Diptera dominated the migratory assemblage, and annual numbers varied by more than fourfold. Numbers at this single site hint at the likely billions of insects crossing the entire Pyrenean mountain range each year, and we highlight the importance of this route for seasonal insect migrants.