Where Have All The Pigeons Gone? Hawking Trafalgar Square

Pigeons ( and other urban wildlife ) have evolved with the development and decay of urban centers world wide. A city would not be a "city" without them. Although Pigeon is a delicacy in some parts of the world in most cities they are as entwined in the landscape as squirrels and mice. How many Pigeons are too many pigeons?  In London's Trafalgar Square a Hawk was introduced to keep the Pigeon population in check the details. h/t PRI The World