That's the question on the island of Hokkaido in Japan, where the revered tancho crane population is at a 100-year high of 1,200, but its natural habitat has shrunk by 30% over the last 60 years. (Total world population for the species is just 2,600, making it one of the world's most endangered birds.)

The crane is an oddity among critters needing conservation. Once thought extinct in Japan, 10 cranes were re-discovered in the 1920s. Three decades later, the species still numbered just 33 birds. But the people of Japan stepped up to preserve the tancho crane, and started actively providing food for the birds. That helped the population grow to its current level -- and also made the species rather tame and almost completely dependent upon humans for its food.

Meanwhile, the marshlands the cranes call home are being replaced by development, and the groundwater level is being depleted by deforestation.

Now, with less marshland to provide food naturally, and no fear of humans, the cranes are even becoming a nuisance, and are feasting on the crops at nearby farms.

So what happens next? Japan's Environmental Ministry is looking into building more sanctuaries, and some experts are warning citizens to stop treating the birds as "pets." And as the Daily Yomiuri points out, the crane still has the normal risks of any species locked into too small a habitat:

 If a large number of the same species are concentrated in one area, it becomes very difficult for them to survive purely on the food they can get in the wild and this increases the risk of massive die-offs due to deadly infectious diseases.
The people of Hokkaido deserve much praise for keeping the tancho crane from going extinct in its home country, but the question of what comes next remains unanswered for this species, at least for now. 

Story by John Platt. This article originally appeared in Plenty in January 2008.

Copyright Environ Press 2008

Endangered Japanese crane outgrowing its habitat
What happens when a species' population rebounds but its habitat is still shrinking?