An interesting article on BBC News about MI5 planning to use pigeons as part of the Fortitude D-Day deceptions.http://news.bbc.co.uk/2/hi/uk_news/7588186.stm
MI5's D-Day pigeon plot revealed
British spy chiefs drew up secret plans to use pigeons to spread false rumours about the impending D-Day landings.
The plot in 1943 to drop the birds into German-occupied France is revealed in newly declassified MI5 files released by the National Archives.
Germany had been intercepting pigeons carrying Allied notes, the files say, so MI5 moved to drop false information.
It planned to put extra pigeons over the west coast of France to give the impression the invasion would be there.
The revelations come in newly-released files on World War II called “Channels for deception”...
This idea was used later for Operation Periwig,
(see my article on Perwig here: http://www.psywar.org/periwig.php