I saw something like this in the City I live in. There were Pigeons everywhere. one day ages ago I was riding my bicycle to college and I saw a hawk fly down to a group of Pigeons hanging around on the ground and grab one. The Pigeons looked surprised and did not know what to do. That was over 40 years ago when Hawks started repopulating the area.

Not long afterwards, all Pigeons started hiding and you do not see many just hanging around. One favorite place is under bridges. Shows animals will learn real fast to avoid threats :)