... 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 … - David Lack

... 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 are larger than the largest swifts.

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.

... Female song is uncommon in birds.