This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2015.
New Zealand Grebe Poliocephalus rufopectus is endemic to New Zealand. It is currently listed as Vulnerable under criterion C2a(i) because it has a very small and fragmented population (<10,000 mature individuals, with all subpopulations ≤1,000 mature individuals), which was thought likely to be declining overall.
The remaining population was restricted to North Island; the reason for the rapid decline and extinction on South Island in the 19th century is not known. However, occasional vagrants have appeared in the north of South Island since the late 1980s and in 2012, a pair bred near Takaka, representing the first confirmed breeding record on South Island since 1941 (K. Owen in litt. 2012). Also, new data is available on population trends, with the population now suspected to be holding its own or increasing (Sachtleben in prep., K. Owen in litt. 2012). The national population has now been estimated to number 1,900-2,000 birds, including c.200 in Northland, c.700 in the Volcanic Plateau, c.400 in the Hawkes Bay, c.150 in Wairarapa and c.400 in Manawatu (Heather and Robertson 1997, Sachtleben in prep.). Thus, the number of mature individuals in the national population is put at 1,200-1,400, based on the assumption that mature individuals account for around 2/3 of the total population. If this information is confirmed, and the population is no longer in continuing decline, this species would warrant downlisting to Near Threatened – nearly meeting the thresholds for Vulnerable under criterion D1.
Further information on population size, trends and size of the largest subpopulation is welcome.
Heather, B. D. and Robertson, H. A. (1997) The field guide to the birds of New Zealand. Oxford University Press: Oxford, UK.