"Yippee ki yay, Mr Falcon."

Trafalgar Square used to be particularly famous for its pigeons, with feeding them a popular activity for Londoners and tourists. However, the resulting pigeon droppings uglify the buildings and damage the stonework, and the flock, estimated at its peak to be 35,000, was considered to be a health hazard.

Consequently, the sale of bird seed in the square was outlawed in 2000, feeding pigeons outlawed in 2003, and feeding any birds outlawed in 2007. In fact, there is now a trained falcon on site to keep the birds away...

See also the Save the Trafalgar Square Pigeons site.