The term EXTINCT BIRD refers to four species of birds that are now extinct: the MOA (3 letters), the DODO (4 letters), the AUK (3 letters), and the ROC (3 letters). The most well-known extinct bird is the Passenger Pigeon (15 letters), which was once the most abundant bird in North America before it went extinct in 1914. All of these birds were hunted to extinction by humans, either for food or for sport.