Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, UK.
Biol Lett. 2023 Nov;19(11):20230355. doi: 10.1098/rsbl.2023.0355. Epub 2023 Nov 22.
Daytime migrants are known to orientate using the position of the sun, compensating for its changing position throughout the day with a 'time-compensated sun compass'. This compass has been demonstrated in many migratory species, with various degrees of accuracy for the actual movement of the sun. Here, we present a model for differing levels of compensation for the solar ephemeris that shows that a high degree of efficiency, in terms of distance travelled, can be achieved without full time compensation. In our model, compensating for the sun's position had a diminishing return with an accuracy of 80% leading to only a 2% reduction in distance travelled. We compare various modes of time compensation-full, partial, time averaged and step-revealing their directional efficiency in terms of distance travelled under an autumn migration scenario. We find that the benefit of time compensation varies with latitude, with time averaging performing very well, especially at all high latitudes, but step compensation performing better at very low latitudes. Importantly, even rudimentary adjustment can dramatically increase the efficiency of migration, which suggests an easy pathway for the independent evolution of time compensation.
日行性迁徙动物会利用太阳的位置来进行定位，它们会通过“时间补偿太阳罗盘”来补偿太阳在一天中位置的变化。这种罗盘在许多迁徙物种中都得到了证实，其对太阳实际运动的准确度存在差异。在这里，我们提出了一个针对太阳历较差补偿的模型，该模型表明，在不进行完全时间补偿的情况下，以行进距离为衡量标准，也可以实现高效率。在我们的模型中，对太阳位置的补偿会随着准确度的提高而逐渐减弱，在 80%的准确度下，只会导致行进距离减少 2%。我们比较了各种时间补偿模式——完全补偿、部分补偿、时间平均补偿和分步补偿，根据秋季迁徙的情景，分析了它们在行进距离方面的方向效率。我们发现，时间补偿的益处随纬度而变化，时间平均补偿的效果非常好，尤其是在所有高纬度地区，但分步补偿在非常低的纬度地区表现更好。重要的是，即使是基本的调整也可以极大地提高迁徙效率，这表明时间补偿的独立进化有一条简单的途径。
