Arizona Daily Star: Enjoy the elegant trogon, a longtime summer visitor to Southern Arizona that now is increasingly staying for the winter. But don’t get too attached to the purple finch, because that mountain bird’s Arizona population has dropped 45 percent since the 1960s. These birds represent two sides of a dramatic northward movement for many bird species nationally over four decades due to climate change, according to a recent National Audubon Society study. Some bird species have shifted their …