Peregrine Falcons, in their normal habitat on isolated cliffs, mate for life. But some 25 pairs now nest on Chicago skyscrapers and bridges, and city living has them in much closer quarters than they used before humans dominated the landscape. A group of Field Museum and University of Illinois, Chicago scientists investigated whether typical breeding patterns hold true for these new city-dwellers and, in a paper published in PLOS ONE, confirmed that even in the big city, the birds that prey together, stay together.