New Zealand scaup (Aythya novaeseelandiae) counts are collated from a total of 12,145 site visits nationally between 1888 and 2018 to estimate their distribution, population status, and trends. Based on systematic counts of large flocks on lakes between 1984–2018, there are about 11,000 New Zealand scaup nationally. This estimate must be interpreted with caution, as if birds are highly mobile the risk of overestimating the population is high. The distribution of New Zealand scaup strongholds (>50 adults) is compared to historical descriptions and trends in water quality. As lakes become more eutrophic over time, the birds move and the population declines. Research should focus on aerial vs ground counts, telemetry/satellite and/or banding studies of bird movement, gender, diet, predation, and littoral zone quantity and quality (<10 m deep). To achieve this, it is recommended that a national waterbird management and monitoring plan be developed.
Understanding how animal behaviours are affected by external factors such as time of day/year and weather conditions is fundamental to understanding the basic biology of a species and can thus help with conservation management. Weka (Gallirallus australis) is typically crepuscular in its habits, but there is some evidence to suggest that it can also be nocturnal. We conducted a longitudinal study of the nocturnal habits of the western weka (G. australis australis) located at Manaroa in New Zealand’s Marlborough Sounds. We used model selection information criterion to examine how the numbers of weka in an open environment (lawn) changed with time of night and season, as well as differing weather and moonlight conditions. In addition, we undertook night-time behavioural observations during a four-month subset of the study period. Numbers of weka declined through the night and increased non-linearly around dawn. Weka were more likely to be present during moonlit nights and at warmer temperatures during the evening. There was considerable seasonal variation, with the highest number of weka during autumn and lowest during summer. Behavioural observations demonstrated that weka were active throughout the night, with foraging being the most frequently-observed behaviour.
Public and our observations during 1999–2004 suggested that tūī (Prosthemadera novaeseelandiae) visited the city of Hamilton during March to October only, outside the nesting season. From 2004 onwards, we captured and banded 51 adult tūī and fitted radio transmitters to 41 in Waikato urban areas to locate nests. We directly observed 15 nests to determine nesting success and gather evidence of any predation events. Tūī moved 5–23 km from urban areas to surrounding native forests at the onset of nesting, but only four (29%) of 14 unmanaged nests fledged young, due mostly to predation by ship rats (Rattus rattus), swamp harriers (Circus approximans), and brushtail possums (Trichosurus vulpecula). Subsequent effective pest mammal control in forests around Hamilton was associated with greatly increased year-round tūī abundance and nesting in Hamilton. These results confirm previous findings that tūī move widely in winter; that they readily cross pasture in the absence of forest corridors, and that they will permanently inhabit urban areas. Provided adequate food is available, effective control of ship rats and possums can rapidly (1–4 years) increase tūī visits and nesting within 20 km of managed sites, enabling recolonisation of proximate urban habitats by this iconic endemic taxon, despite previous evidence for natal philopatry.