Carrier pigeons are common domestic pigeons, or rock doves (Columba livia), that have been trained to fly back to human-tended lofts on being released with messages attached to their tail feathers or legs. For hundreds of years, carrier pigeons have been used extensively to send long-distance messages, and in the 19th and 20th centuries, they became an essential backup communication tool in situations where more modern technologies failed or were impractical, particularly in wartime. Pigeons were also one of the first unmanned aerial surveillance technologies; they were successfully used for airborne photography more than 100 years ago. Even in recent times, information transfer has been carried out covertly through this secure, low-technology means. This entry first reviews the capabilities and early uses of carrier pigeons, then discusses their usage during wartime, followed by an examination of how carrier pigeons have been utilized for intelligence gathering and military usage, among other purposes.
Pigeons were domesticated thousands of years ago; they show little fear of people and have become accustomed to living in close quarters with human society. The attribute that has made pigeons most useful to humans is their ability to home, or navigate accurately back to their living quarters over long distances. Pigeons become attached to the home lofts in which they were raised, and when they are removed from these surroundings to a location foreign to them, they will faithfully and quickly return to the home loft, even without having line-of-sight or visual information from the outbound voyage. With training, they can be habituated to new home lofts and to recognize mobile lofts moved relatively short distances, though they work only in one direction (two-way homing pigeons were trained in the 20th century with limited success and did not see general use). Their speed exceeds 60 miles per hour in good wind, and they can home over hundreds, or even thousands, of miles; one pigeon, released in France in 1931, returned 24 days later to its home loft in French Indochina, 7,200 miles away. There does not appear to be a single explanatory mechanism for how pigeons accomplish this feat. They do not rely heavily on sight to navigate, though they do use some visual clues, even following human roadways at times. Experiments by pigeon biologists indicate that sun orientation, olfaction, and compassing using the earth’s magnetic field all have some impact on their ability to home.
Accounts of the wartime utility of pigeon messenger services date back as far as Julius Caesar. Pigeons could be used to keep officials informed of developments on front lines and to move troops more efficiently. The siege of Paris by the Prussians in 1870–1871, however, saw the French employ military carrier pigeons to previously unknown effect. Prior to the surrounding of the city, pigeons from the countryside had been brought into Paris; pigeons homed in Paris were sent up with refugees in balloons, allowing for two-way communication. Much refinement of message attachment technique occurred during the siege. Originally, messages were wrapped, waxed, and attached to the feathers, but many of the messages fell off from the birds. Instead, now papers were curled inside the hollow quills, which were tied together at the ends and then attached to the birds’ tails. (Later, canisters were developed that were attached to the pigeons’ feet or strapped to their backs.) The Parisians used microphotography to copy the communication onto collodion films, allowing a single bird to carry more than 30,000 words. In the 4 months when Paris lay besieged, some 150,000 official communiques and 1 million private messages were sent via carrier pigeon, despite the Prussians’ use of hawks as a counterstrategy.
The success of the Paris pigeon post led many European nations to establish military pigeon stations. In World War I, the birds were used extensively; they allowed for communication at a distance when telephone or telegraph wires were cut, and they were issued to airplanes, tanks, minesweepers, and warships to send progress dispatches or distress signals. Carrier pigeon success rates were greater than 90%, according to many military reports, though they were generally considered reliable only over distances of about 100 to 200 miles. Their importance was such that the German forces ordered the destruction of all pigeons found in the overtaken territories. One of the most famous carrier pigeons of the war, Cher Ami, was sent up by the “Lost Battalion,” an American unit that had inadvertently become surrounded by German forces in the Argonne Forest and was subjected to friendly fire. Cher Ami was shot through the breast almost immediately after release but still managed to home back to headquarters in less than half an hour, the message containing the unit’s coordinates hanging from the shredded remains of its leg.
Pigeon use for military ends continued to expand in World War II. In 1938, the British established a National Pigeon Service in anticipation of war and put more than 200,000 pigeons into use for military and civilian communication. They were often standard issue for aircraft, naval vessels (including submarines), and paratroopers and enabled multiple rescues of the crews of downed planes and sinking ships. The first information relayed back to Britain during the D-Day invasion, under conditions of radio silence, arrived via Gustav, a pigeon who returned 5 hours after being released from the Normandy beachhead. The Dickin Medal, established in England to honor the efforts of wartime animals, was awarded to 54 creatures for service in World War II—32 of the recipients were carrier pigeons.
In the first decade of the 20th century, it was found that homing pigeons could facilitate photographic surveillance as well. Julius Neubronner, a German pharmacist who used pigeons to transfer prescriptions and medications, strapped small cameras with pneumatic shutter systems to the pigeons’ chests. Once the birds were airborne, the slowly releasing air from a rubber ball closed the shutter at regular intervals. If timed properly, the pigeon photographer could return with a continuous visual record of its flight path. Neubronner patented the device in 1908, and soon afterward, the German military adopted it for topographic reconnaissance. Camera-bearing pigeons were occasionally shot down by the Allied forces in World War I, though their use seems to have been minimal afterward. While the typical method of deployment was via aircraft, the birds would also be trucked to areas where they could fly over enemy land, and on at least one occasion in World War II, the Germans attempted pigeon surveillance of Russian territory using dogs trained to release them from pack-baskets. The CIA explored pigeon reconnaissance possibilities in hope that it would provide better-resolution images than high-flying aircraft, though the extent of this usage is not known.
Even more exotic uses of birds as biosurveillance and biowarfare tools were imagined. Classical conditioning using food was the most popular training technique, as many birds respond to this well; for instance, the British threw bread from surfaced submarines so that seagulls would learn to associate the vessels with food, the better to detect submerged U-boats. The CIA considered attaching explosives or biological weapons to pigeons during the Cold War. Behavioral psychologist B. F. Skinner trained pigeons to home on pictures of targets, with the intent of using them to guide missiles. While this never saw actual use, it was taken seriously enough by the U.S. military so that several years were spent in the 1940s and 1950s investigating its efficacy. Inspired by Skinner, other researchers taught birds to identify the human form, with an eye toward ambush detection and search-and-rescue. While pigeons were found in Coast Guard experiments to be even better than humans at spotting orange life vests over open water, they never came into use in this capacity. In the 1970s, it was found that pigeons could be trained to differentiate between natural and man-made objects, and the feasibility of using this to have the birds detect and gather visual (via photography) or locational (via remote sensing) information about structures was explored. More recently, pigeons with tracking devices and air pollution sensors have been used for smog monitoring in California.
See also Aerial Reconnaissance and Surveillance ; Surveillance During World War I and World War II
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