Terrestrial vertebrate survey of Motukawanui

We describe the history of Motukawanui, the largest island of the Cavalli Islands, off New Zealand’s Northland east coast, and report on a survey of terrestrial vertebrates undertaken in February 2020. We compare our findings to the previous published survey conducted in December 1979–January 1980. Over the last 40 years, the island’s landscape has changed dramatically from one of farmland to predominantly native forest. As a result, the habitat has shifted toward supporting a larger assemblage of endemic and native birds, and away from supporting those that are non-native. Kiore, or Pacific rats (Rattus exulans), remain abundant across the island, though densities are lower compared to estimates of the previous survey. The richness of reptile species also appears to have declined over the past few decades. Overall, we suggest Motukawanui is a relatively straightforward island from which to eradicate rats. Such an eradication would require approval from local iwi but would directly contribute to meeting interim goals of the Predator Free 2050 initiative.