A friend recently invited me over to see the blackbird that had taken up residence in a potted plant on her balcony. Serenely incubating eggs in the inner city, this bird had little in common with its shy, reclusive ancestors that nested in Europe’s forests. Early in the 19th century, probably in Germany, blackbirds began settling in cities. By the mid-20th century, they were hopping around on stoops all over Europe. Many “wild” bird species…