 Each of the four of the standard-format Pigeon books has been on the New York Times best-seller list.A 2011 scientific study entitled "Let the Pigeon Drive the Bus" examined the ability of pigeons to solve the traveling salesperson problem by taking the shortest route to visit multiple feeders in a laboratory.The authors found that pigeons "appeared to plan ahead multiple steps," which provided "clear and strong evidence that animals other than primates are capable of planning sophisticated travel routes."