The island of Santa Cruz is the second largest island in the Galapagos and is about 380 square miles in size. It contains two populations of tortoises—one that resides on the southwestern part of the island, known as the “La Reserva” group, and one on the eastern part, about 12 miles away called the “Cerro Fatal” group. The Reserva group is a bit larger, with 2,000-4,000 individuals to Cerro Fatal’s few hundred. Tortoise species on other islands differ in size, carapace (shell) shape and length of necks, but physically, these two don’t appear to be that drastically different despite some slight differences in carapace shape. Ecologist Nikos Poulakakis of the University of Crete, coauthor of the study, notes that the Cerro Fatal tortoises have more compressed carapaces than the elongated carapaces of the Reserva tortoises.