... many large insects come out at dusk. By doing so they escape many enemies, but not all, since here the nightjar tribe takes over, many of which a… - David Lack

The limicoline species in June and July, and the passerine species in late autumn, cross the North Sea primarily with easterly winds and hardly at all with westerly winds, whereas in spring they often set out against the wind. This might merely be due to a stronger migratory urge in spring than autumn, but it also seems possible that westerly winds deter migration in autumn because they are so often associated with rain and other unfavourable conditions.

In Lapland, all species start breeding 1–2 months later than in Britain, and the breeding season is much less extended. As compared with Britain, the Corvidae and predatory birds of Lapland lay early relative to the small passerines, but among the small passerines, and also among the predators, the different species tend to breed in the same order relative to each other as they do in Britain.

... It is uncommon among birds for the female to be as brightly coloured as the male. ... A brightly colored female would be much more dangerous for a species which nested in the open.