Quokkas on Rottnest Island, WA, have been virtually free of predation for about 7,000 years. Researchers have found that despite long isolation from predators and therefore relaxed natural selection, quokka showed typical group-size effects. They foraged more and looked around less as group size increased. In a similar study of western grey kangaroos, an insular population living with limited risk of predation did not exhibit the typical group-size effects observed in mainland populations subject to predation.