New Caledonia's animal land diversity was similar to that of some oceanic islands, particularly New Zealand and as in these islands, the biodiversity was greater before being inhabited by humans. The island has no native mammals except for bats and no native amphibians. The vertebrates are dominated by reptiles and birds. Today the island has 21 endemic species of birds, including one endemic family, the Rhynochetidae, represented by one living species, the kagu. The island is also home to the unusual tool-using New Caledonian crow. The separation of the Gondwana islands before the mammalian expansion that allowed the radiation of flightless birds (moa, kiwi, sylviornis, cagous) and Mesozoic reptilian forms such as the tuatara of New Zealand.