"In areas (((in occupied France))) where we had no direct contact with the Resistance movement, we used to get our bombers to drop homing pigeons in containers which would open after a few hours and release the birds if they had not been found by someone on the ground.
"Attached to the containers were questionnaires, asking a series of simple questions which, for example, a farm labourer might be able to answer, and which might be helpful to us. My own question was: 'Are there any German radio stations in your neighbourhood with aerials which rotate?' This feature was an almost certain criterion of a radar station, and we dropped the pigeons wherever we saw a gap in our knowledge.
"Before the end of 1942 the pigeons had given us the locations of three stations hitherto unknown to us, and more followed during 1943."
"(...) fortunately a heavily-laden and very gallant pigeon arrived at its home base, having been dropped by Bomber Command somewhere in North France with my usual questionnaire. It had been picked up by a Frenchman who had been present in one of the German nightfighter control stations, perhaps as a cleaner, and when he saw that there was a question about radar he had clearly delighted in describing the events one night in the station at le Croix Caluyau as he had witnessed them.
"I have never seen a pigeon carrying such a profuse message. It ended with the exclamation by the German Commander, who had spent the night trying to intercept seven hundred separate bombers without being able to locate one: 'He would rather be attacked by a hundred bombers than submit to that torrent of paper again!'"
(((Lars-Erik Astrom remarks: This was the British radar countermeasure, the Window project: they filled the air with lots of metal foil strips to clutter the German's radar vision.)))
"Another wartime experience that made me wonder was the ability of pigeons which had spent their entire lives in England to home back to their bases after we had dropped them on the Continent. I spent some time with the Air Ministry Pigeon Service in the months after the war, learning from experts what pigeons could do."
"Geographical landmarks, though, could not explain a good deal of the wartime flying, and I began to wonder whether the birds had developed a form of inertial navigation, based on the semicircular canals in their heads, which were known to be accelerometers. We tried to keep the Air Ministry Pigeon Service in being after the war, with a view to organizing a prolonged series of experiments, but the scheme fell through when both the pigeons and I left the Air Ministry."
Lars-Erik Astrom (firstname.lastname@example.org)