Big Bird Reintroduces Itself

It is interesting to read that, after a 400 year absence, the Common crane (the animal pictured is the related Red crowned crane) has reintroduced itself to locations in the Eastern UK (https://www.theguardian.com/environment/2018/jul/17/common-cranes-here-to-stay-after-recolonising-eastern-england). They now appear to have a viable and growing population, already qualifying as Britain's tallest bird. I suspect that this self-introduction is more related to changes in human responses to the bird than any other factor.