Hi, in discussing night flight calls I am a bit confused about the concept of "night". Astronomically, I have no problem with the true night, and the various twilights. If the limit of "night" is taken at sunset/sunrise, then various day birds fall into the category of night flight calling birds even if they are not proper night migrants. Tits (chikadees), crows and finches start to vocalise before well sunrise, during the civil twilight, and gererally they do not crowd the sky in the deep hours of the night. There appears also to be an assymetry between dusk and dawn. During the same light conditions the duirnal birds at dusk tend to be much quiter than at dawn, so this is not that miuch of a problem in the evening. My question is when do you guys consider the night over? Regards Harry [email protected] Finland
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