Many plants and animals are assumed to belong to the Mauritian ecosystem. In fact, they were deliberately or accidentally introduced to the island by man. The alien species displace native species through competition for limiting resources, they may prey upon native species to the point of extinction, such as the Dodo, they may alter the habitat so much that natives are no longer able to persist. For example, Dutch colonisers introduced the Rusa deer from Indonesia and East Timor in 1639, and grazing by these deer hinders native forest regeneration and helps spread invasive plants, such as Chinese guava. With settlements increasing in Mauritius, the need for food increased and more exotic animals were introduced-goats, pigs, cattle and dogs, ate the native vegetation and wildlife. Millions of rats found their way onto the island. Soon cats and mongooses were introduced to control rats, but ended up eradicating many endemic species. Even today, exotic animals continue to threaten the survival of many native plants and animals. Long-tailed macaques directly competes with the endemic fruit bat for food resources in the forest. Macaques are responsible for damaging majority of the forests’ reproductive outputs (i.e., flowers and fruits) and hinders forest regeneration.