Why do bird sings outside your window very late at night?

There are several reasons why a bird might sing outside your window late at night.

Migration: During the spring and fall migration seasons, birds may sing as they travel at night. They do this to maintain contact with other members of their flock and to navigate.

Territorial Defense: Birds may also sing late at night to defend their territory. This is more likely to occur during breeding season, when birds are competing for the best nesting spots.

Attracting a Mate: Male birds may sing at night to attract a female mate. This is most common during the breeding season.

Light Attraction: If your window is lit, it may attract insects, which birds may be seeking out as food. As they search for insects, they may sing.

Circadian Rhythm Disruptions: Artificial lights from urban areas can disrupt the natural circadian rhythms of birds, causing them to sing at unusual hours of the night.

It's important to note that not all birds sing late at night, and the specific reason why a bird might be singing outside your window may vary. If you find it disturbing, you may consider using blackout curtains or blinds to block out the light and reduce the attraction to insects.