Do dragonflies migrate across the western Indian Ocean?
Do dragonflies migrate across the western Indian Ocean?
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DOI：
10.1017/s0266467409006087
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发表时间：
2009-07-01
影响因子：
1.4
通讯作者：
Anderson, R. Charles
中科院分区：
文献类型：
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作者：
Anderson, R. Charles
在热带印度洋，马尔代夫群岛缺乏地表淡水。因此不适合无性繁殖。然而，每年十月开始，数以百万计的蜻蜓（昆虫纲，蜻蜓目：大多数是地球仪掠食者，Pantalaflavescens）突然出现。到达马尔代夫和印度的日期表明，蜻蜓从印度南部旅行，距离约500-1000公里。到达和发生的日期与热带辐合带（ITCZ）的南行相吻合。间接证据表明，蜻蜓在ITCZ内和ITCZ后，在1000米以上的高度随东北风尾风飞行。有人提出，这种大规模的蜻蜓运动是从印度到东非的西印度洋年度迁徙的一部分。抵达塞舌尔的日期支持这一假设。5月，随着西南季风的到来，马尔代夫也出现了蜻蜓（数量较少），这表明可能有来自非洲的回归迁徙。这些蜻蜓的迁徙，定期穿越3500亲属或更多的开放海洋，以前是未知的。众所周知，这些蜻蜓利用短暂的雨水池进行繁殖;季风和ITCZ不仅为印度和非洲带来交替的季节性降雨。也有适合蜻蜓跟随雨水的风。有几种鸟类从印度出发，穿越西印度洋，到非洲过冬。它们与蜻蜓同时这样做，大概是利用了同样的季节性顺风。许多这些鸟类也吃蜻蜓：这可能的重要性以前没有被认识到。
In the tropical Indian Ocean, the Maldive islands lack surface freshwater. so are unsuitable for dragonfly reproduction. Nevertheless, millions of dragonflies (Insecta, Odonata: mostly globe skimmer, Pantalaflavescens) appear suddenly every year starting in October. Arrival dates in the Maldives and India demonstrate that the dragonflies travel from southern India, a distance of some 500-1000 km. Dates of arrival and occurrence coincide with the southward passage of the Inter-tropical Convergence Zone (ITCZ). Circumstantial evidence Suggests that the dragonflies fly with north-easterly tail winds, within and behind the ITCZ, at altitudes over 1000 m. It is proposed that this massive movement of dragonflies is part of an annual migration across the western Indian Ocean from India to East Africa. Arrival dates in the Seychelles support this hypothesis. Dragonflies also appear (in smaller numbers) in the Maldives in May, with the onset of the southwest monsoon, suggesting a possible return migration from Africa. These proposed migrations of dragonflies, regularly crossing 3500 kin or more of open ocean, were previously unknown. It is known that these dragonflies exploit ephemeral rain pools for reproduction; the monsoons and ITCZ bring not only alternating, seasonal rains to India and Africa. but also appropriate winds for dragonflies to follow those rains. Several bird species migrate front India across the western Indian Ocean to wintering grounds in Africa. They do so at the same time as the dragonflies, presumably taking advantage of the same seasonal tail winds. Many or these birds also eat dragonflies: the possible significance of this was not previously appreciated.