Arboretum. The Amur Corktree, a native of China and Japan, bears a passing resemblance to our walnut trees. But when the fruit appears it is easy to see it is quite a different tree. This species is hardy in our climate, and has recently become a bit of a problem in natural areas where it has the potential to become yet another invasive species. However, the fruit of this tree feeds many birds, not just starlings. There was also a small flock of robins feeding on the fruit, and waxwings of both species will also eat it. This of course, is how it spreads!