Abstract
Blue duck/whio (
Hymenolaimus malacorhynchos) are nationally endangered. Internal management guidelines have recommended surveying populations to estimate their size and range. This survey is a repeat of a previous one done over the summer of 1999/2000 to estimate the population in a number of the rivers in the north west catchments of Kahurangi National Park. The results showed very little change in numbers of whio seen in comparison with the previous survey. In 1999/2000 the survey found 54 adults made up of 19 pairs and 16 singles with 24 ducklings whereas in 2009 there were 52 adults made up of 16 pairs, 20 singles with 5 juveniles and 4 ducklings. The second survey was later than the first which may have led to fewer ducklings being detected. Almost half of all whio (six pair, eight singles and two juvenile) were found in just two areas - Gouland Downs and the Waingaro River.