The floor of Honeycomb Hill cave in the Ōpārara Valley, Kahurangi National Park, is littered with fossils – bird, amphibian and reptile bones. Extinct native bird fossils date as far back as 20,000 years. New Zealand cave fossils are unique in showing how species changed as the climate warmed around 12,000–9,000 years ago. At this time elsewhere in the world, animals were subject to hunting by humans. There were no people in New Zealand, so scientists know that any changes were due to climate change.