Regarding assisted migration:
I have been checking in on the Operation Migration cam recently. This group is based in the US and is working to reintroduce Whooping Cranes. In the 1940s, there were only 14 individual birds left! Now there are about 500. In this project, the eggs are incubated and hatched in a facility in Patuxent, Maryland, then flown to a refuge in Wisconsin where they are raised. The chicks are trained to follow an ultralight aircraft and after several weeks of short and then longer flights, they follow the aircraft to wintering grounds in Florida. After that first time, they migrate on there own. All very complicated!
http://www.operationmigration.org/
cam link:
http://www.wildearth.tv/web/omi-cam-01? ... omi-cam-01 (early morning their time is when training takes place, or click on one of the "hotspots" to see an interesting segment from the archives)
Anyway, I asked my wildlife rehabber/nutritionist friend why these birds needed to be shown the way, when other birds simply seem to "go." She replied that all birds have an innate sense (?perhaps a genetic memory) but some species needed to have the instinct "unlocked."