This is a thread about zoo birds, not wild birds living on zoo grounds. Several zoos in Europe keep free-flying colonies of White Storks, which partially helped recovery of this species in Western Europe in the late 20. century. Are there any other examples when zoos established colonies of free-flying birds which spread free and helped conservation? And why it is not done more often? Any zoo in Europe tried to keep freeflying waldrapp ibises, Dalmatian pelicans, ferruginous ducks or any other native birds locally threatened? Any zoo in the southern USA tried keeping freeflying thick-billed parrots?