energy in this aquatic species is documented as lower, using less oxygen when moving on land than locomotion in water. Rakali have the capacity to run at twice their maximum swimming velocity. Their metabolic rate increases during running at a rate of 13-40% greater than when swimming. Predators and predation Humans have been their greatest predator, with rakali requiring protection by legislation in 1938. They were hunted for their soft fur and considered a pest species. Populations are considered to have recovered and in all states considered of 'least concern' with the exception of Western Australia. Considered a pest in irrigation systems due to burrowing into banks and creating leaks, in a positive sense they have also been attributed to reduction of bank damage as they prey on freshwater crayfish (yabbies). Predators of the rakali range from large fish and snakes when they are young and in the water, to birds of prey, foxes and cats. The rakali has the unusual ability to kill cane toads without being poisoned. Behaviour and life history Nesting The breeding behaviours are influenced by seasonal conditions. Under good seasonal conditions the solitary water rat comes together with their mate and may produce several litters (if young are removed will reproduce again within two months), but separate on the birth of the young. Limited information is available on home range, but suggests localised movement around the nesting sites and foraging areas. Rakali construct burrows dug into river banks but have also been documented building nests within sunken logs and reeds, in areas surrounded by roots and dense riparian vegetation for cover from predators. There is increasing evidence of altered nesting habitat with rakali using artificial shelters of drainage pipes, exhaust pipes in moored boats, and rubber tyres in human-modified areas. This occurs more frequently in high population density situations. Breeding and growth Females are able to reproduce from one-year-old or 425 g. Mating commences from late winter to early spring with a gestation period of 34 days. Rakali have four mammae with nipples located in the abdominal inguinal area enabling litters of an average of four to five are born from September to February and are suckled for four weeks. Sexual maturity develops at around twelve months but has been documented to commence at 4 months and breeding in the season of their birth. They are able to continue breeding until females are three and