Three uninvited English sparrows who snuck into the structure before closure thrived merrily. Leigh complained that the sparrows were brash and noisy, even vulgar in their pushiness, while the finches were elegant, peaceful, and melodious singers. Keep the sparrows and forget about the finches. The problem was not just sparrows. It was aggressive passion vines in the artificial savanna, and savanna grasses in the desert, ants everywhere, and other creatures not invited.
Urbanization is the advent of edge species.
The hallmark of the modern world is its fragmentation, its division into patchworks. What wilderness is left is divided into islands and the species that thrive best thrive on the betweenness of patches. Bio2 is a compact package of edges. It has more ecological edges per square foot than anywhere else on Earth. But there is no heartland, no dark deepness, which is increasingly true of most of Europe, much of Asia, and eastern North America.