Animals have always been central to author Sara Gruen, an expatriate Canadian who now lives in western North Carolina.There were the circus animals, of course, in Gruen’s runaway best seller, “Water for Elephants,” including an elephant who deals out rough justice. Beyond that, there were the horses in her early novels and the bonobos who figured in her novel “Ape House.”In her latest, “At the Water’s Edge,” though, Gruen goes [...]