I saw this post this morning and just loved the absurdity of the idea, as well as the actual images produced. *LINK*
"In 1908 Dr Julius Neubronner patented a miniature pigeon camera activated by a timing mechanism. The invention brought him international notability after he presented it at international expositions in Dresden, Frankfurt and Paris in 1909–1911. Spectators in Dresden could watch the arrival of the camera-equipped carrier pigeons, and the photos were immediately developed and turned into postcards which could be purchased."
(All images from the National Air & Space Museum Spy Technology Section via Wikimedia Commons)