Operation Migration was a nonprofit, charitable organization, which developed a method using ultralight aircraft to teach migration to captive-raised, precocial bird species such as Canada geese, trumpeter swans, sandhill cranes, and endangered whooping cranes. Background Operation Migration Canada was founded in 1994 as a Canadian registered charity. Operation Migration-USA Inc was established in 1999 as a 501(c)(3) nonprofit organization. In collaboration with the Whooping Crane Eastern Partnership, Operation Migration participated in the reintroduction of endangered Whooping cranes into eastern North America beginning in 2001 and continuing until the last small flock was lead south in 2015. It is believed by conservationists that approximately 500–1,400 whooping cranes existed in 1860. Their population declined because of hunting and habitat loss until 1941 when the last migrating flock dwindled to an all-time low of 15 birds; all birds of this species alive today are descendants of this flock. The wild flock has slowly increased to 506 in 2021. This flock winters in and around Aransas National Wildlife Refuge on the Texas Gulf Coast. In spring, they migrate north, nesting in Wood Buffalo National Park, which straddles the border of Alberta and Northwest Territories in Canada. This flock of whooping cranes is the only naturally occurring wild population in the world. Scientists have long recognized the risk of having all of the wild whooping cranes using one wintering and breeding location. With all the wild birds concentrated in one small area, the population could be wiped out by disease, bad weather, or human impacts. Whooping crane survival depends on additional, separated populations. Operation Migration helped to establish a reintroduced population which migrates along an eastern pathway; this group has 81 individuals as of 2021. With an additional 79 individuals considered wild and non-migratory and 136 individuals in captivity, there are 802 whooping cranes in the world as of data collected in 2021. Imprinting, training, and releasing cranes The whooping crane chicks are transported to Wisconsin in June where they are conditioned to follow ultralight aircraft in preparation for their fall migration to wintering grounds in Florida. Pilots lead the birds on training flights over the White River Marsh State Wildlife Area in Green Lake County, Wisconsin throughout the summer to build the birds' stamina. Each year since 2001, a class of cranes has been led on their first migration south from Wisconsin to Florida's Gulf Coast. Beginning in 2005 the ultralight-led migration was supplemented