If you cross the Manes Bridge (Manesuv most) towards the Lesser Town, on the left you can walk down to the river banks where there is always a large group of swans and other seabirds gathering to be fed by the locals. And if you’re lucky, you might see some river rats amongst them. The swans do not like these intruders and chase them off with their loud hisses! Don’t forget to take photos of the nice view of Charles Bridge and the Old Town in the background.
Swans hissing at a coypu near Manes Bridge