Papua New Guinea notable feature in common for the two landmasses is the existence of several species of marsupial mammals, including some kangaroos and possums, which are not found elsewhere. Papua New Guinea is a megadiverse country. Many of the other islands within PNG territory, including New Britain, New Ireland, Bougainville, the Admiralty Islands, the Trobriand Islands, and the Louisiade Archipelago, were never linked to New Guinea by land bridges. As a consequence, they have their own flora and fauna; in particular, they lack many of the land mammals and flightless birds that are common to New Guinea and Australia. Australia and New
Herding dog sheep to graze while preventing them from eating valuable crops and wandering onto roads. Herding instincts and trainability can be measured when introducing a dog to livestock or at noncompetitive herding tests. Individuals exhibiting basic herding instincts can be trained to compete in herding trials. In Australia, New Zealand and the United States herding dogs are known as "working dogs" irrespective of their breeding. Some herding breeds work well with any kind of animals; others have been bred for generations to work with specific kinds of animals and have developed physical characteristics or styles of working that enhance their ability