Laysan ducks, one of the world’s most endangered waterfowl, are native to only the Hawaiian archipelago. For 150 years, Laysan ducks were restricted to an estimated 4 square kilometers of land on Laysan Island in the northwestern Hawaiian Islands. In 2004 and 2005, in an effort to rebuild the population, biologists released 42 Laysan ducks on Midway Atoll, located one day’s boat ride from Laysan. By 2007, a breeding population was well established on Midway, reaching 200 ducks. However, in August 2008, more than half of the Midway duck population (181 ducks) was lost to a disease epidemic lasting 30 days. Necropsies (the animal equivalent of autopsies) on dead birds revealed botulism type C as a cause of the die-off.