Evening migrations

Every winter thousands and thousands of corvid birds (mostly Corvus frugilegus and Corvus monedula) from the east visit our cities. They spend nights in large groups in the parks, inside the city. As the sun goes up they fly to the suburbs and fields close to the town. When the sunset is near, they create large swarms and return to their places of night's rest.

My wife wrote her master's thesis about these migrations. We were observing them in the early hours and when it was dark. Sometimes temperature was reaching -40 degrees C, and we had to stand still for a few hours! That were really hard moments