Publications Archive

Abstract: Wing areas and wing loadings of New Zealand land birds are poorly documented in the literature. I therefore report measured wing areas of 84 individual birds belonging to 27 species, with calculated wing loadings. Plotting the data graphically allows some ecological inferences. Heavier New Zealand land birds achieve greater wing loadings than lighter species, as is the case for birds generally. For flying birds, small passerines had the lowest wing loadings (0.12 g/cm2 for the New Zealand fantail) and heavier non-passerines the highest wing loadings (0.88 g/cm2 for the pukeko). I expected non-migratory, forest-dwelling, endemic song-birds with weak dispersal abilities to have very high wing loadings but this was not the case. Instead, native and introduced song-birds of similar size tended to have fairly similar wing loadings. Wing loading was slightly elevated in the North Island saddleback and North Island kokako but the whitehead was normal. The tui, a vigorous flier, had a much lower wing loading than expected for its mass. Data for three flightless species suggest that while high wing loading is an important correlate of flightlessness, it is not the only factor.

Abstract: New Zealand conservation managers use aerial 1080 (sodium fluoroacetate) to control invasive mammalian predators, often with the aim of protecting populations of threatened endemic birds. Matātā (South Island fernbird, Poodytes punctatus punctatus) are endemic to New Zealand wetlands and are vulnerable to mammalian depredation. Mātātā populations might benefit from aerial 1080 predator control, but they also can suffer non-target poisoning losses. This study measured the short-term effects of an aerial 1080 operation on mātātā adult survival (i.e. non target mortality) and nest survival (over one breeding season) on the West Coast of South Island. The study utilised two sites, with an October (mid-breeding-season) aerial 1080 operation at one of the sites. We found no evidence of a negative short-term effect of aerial 1080 – none of fourteen colour-banded adult mātātā exposed to 1080 baits died of 1080 poisoning. Conversely, we found evidence of a short-term positive effect – aerial 1080 improved mātātā nest survival over one breeding season. The presence of a positive effect, in the absence of a negative effect, suggests that the net effect of the 1080 operation for the mātātā population was positive, at the end of the breeding season.

Abstract: Bird abundances on a small island (150 ha) near the mainland of northern North Island New Zealand were studied using a standardised, longitudinal survey through 38 years (1988–2020), a period during which habitat restoration, reintroductions of five native bird species, and control of rats (Rattus spp.) and stoats (Mustela ermina) occurred. We estimated time-series abundances of 33 bird species and found substantial population shifts shared by many taxa. The unique data set from this restoration project showed that: (1) more species and more individual birds were present at the end of the study than at the beginning; (2) rat control made an immediate and lasting difference, increasing population growth of the typical species 6% per year; (3) boosting ecological succession by habitat conversion and habitat enrichment resulted in a long term population growth of many native bird species; (4) shifts in species composition are still ongoing 20 years after predator control, with both gradual, long-term increases, and declines. In particular, two endemic species, and pōpokotea (whitehead, Mohoua albicilla) proved robust competitors in a predator- free environment, increasing in abundance, while most non-native and many native species declined. These gradual, longer-term shifts became clear during “maturation”, a period beginning about 13 years after predator control started.