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Migration

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This figure is a simplified world map on which the flight paths of a single female bar-tailed godwit between sites in Alaska (marked A), New Zealand (B) and China (C) are shown as white arrowed lines. White circles at points along these lines indicate the locations at which satellite signals, 36-40 hours apart, were received. From start to finish of the direct outward journey from Alaska to New Zealand, there are five signal reception sites, which are fairly uniformly spaced, indicating a fairly constant flight speed. The five signal reception sites for the first stage of the return journey, from New Zealand to China, get progressively closer together, indicating a reduction in flight speed as the journey progressed; the last two are very close together, indicating that the final miles of the approach to Yalu Jiang were very slow. For the second stage of this journey, from China to Alaska, the one satellite signal between the start and finish sites was received after about 60 per cent of the journey was completed, indicating some slowing down.

 1.1 Examples of animal migration