They're being replaced by ecologies useful to humans, here a variety of crops and the like. I'm unconvinced that the land should exist for some specific species of mice and birds, but not for us.

All I really hear is that some very small group of aesthetically-minded human apes are precious about one more variety of bird, against the interest of very many other human apes that need to eat.

If the new ecology were really extremely desolate, we might weigh up this a little differently, sure. But the article's entire analysis is that these new ecologies are genuinely "natural" in the sense of self-sustaining, and varied, and so on.