Publications Archive

The yellow-eyed penguin (Megadyptes antipodes) on the South Island of New Zealand was believed to have suffered a population decline that continued into the 1980s. Unpublished census results from L. Richdale (1930s-1950s) and S. Sharpe (1950s-1960s) for Otago Peninsula show that there were only 44 nests in 1940, but the number increascd in the 1940s-1960s. Numbers peaked at 276 nests in the mid-1980s. Subsequent decreases and a crash to 79 nests in 1990 led to concerns for the viability of the population, but years of good survival and breeding allowed a recovery. The fluctuations were probably drivcn by interplays of human impacts and environmental variation. Reservation of breeding areas, revegetation, and predator control have reduced the deleterious human impacts and given the species a chance to increase numbers and withstand adverse fluctuations in the cnvironment.

We investigated the effect of jetboat wakes on feeding wrybill (Anarhynchusjontalis), banded dotterel (Charadrius bicinctus), black-billed gull (Lams bulleri), and black-fronted tern (Sterna albostriata) on the Dart River, Otago. We found that all species feed in areas likely to be affected by jetboat wake. On average, banded dotterel (n=8) were 43.2 mm above the water level and 4.37 m from the waters edge, wrybill (n= 16) were 49 mm above the water level and 0.8 m from the water’s edge. Jetboat wake (n=7) extended 91.3 mm above the waters edge and on average 1 m from the edge of the river channel. The implications of the wash and the extent of the likely effect are discussed.

Bird records from the Snares Islands between Dec 1982 and Oct 2000 are summarised. Population estimates and distributions are given for the 29 breeding species. Bird species recorded breeding on the Snares Is for the first time since 1982 were southern black-browed albatross (Diomedea melanophrys), Chatham Island albatross (D. eremita), mallard (Anas platyrhynchos), southern black-backed gull (Larus dominicanus), fantail (Rhipidura fuliginosa), and starling (Sturnus vulgaris). Fantails are now abundant on the Snares Is. Published work on the breeding chronology and breeding success of 8 intensively studied species is summarised, and new information on breeding ecology is presented for all breeding species. Sighting of 70 non-breeding and vagrant species are summarised; 34 of these were new records from the Snares Is since 1980. The total bird list for the Snares Is is now 99 species, with a further 8 species reported from boats offshore.

The population of white herons (Egretta alba) at Waitangiroto Nature Reserve has been monitored since 1944. The number of breeding adults (estimated from maximum number of nests at the height of the breeding season, and first recorded in 1958) has increased from 26 to c.100, with a concurrent increase in the number of chicks hatched and fledged. Population growth was greatest between 1964-69 and 1980-84. Chick mortality appears to result largely from the effects of westerly and southwesterly storms in October and November, although infanticide, siblicide, and low levels of predation may account for some chickdeaths. The mean number of fledglings nest-I has decreased over time as the number of nests has increased, suggesting a density dependent response. The white herons that “invaded” New Zealand from Australia in 1952 and 1957 did not appear to recruit into the breeding population.

The benefits of monitoring habitat use patterns of translocated populations are widely acknowledged. However, this monitoring seldom occurs. Here, I report the habitat use and foraging patterns of a newly translocated population of South Island saddlebacks (Philesturnus carunculatus carunculatus) on Motuara Island, New Zealand, during the 1st breeding season after release. Reintroduced South Island saddlebacks spent most foraging time on the ground and in Pseudopanax arboreus. Foraging substrates used by male and female saddlebacks differed significantly Saddlebacks focused foraging activities at 0-4 m above ground, and appeared to prefer to forage in larger trees, although the species composition of forested areas did not seem to influence the birds’ choices of places to settle. With increasing population density, saddlebacks on Motuara Island may increase their areal foraging eficiency by using a wider range of plant species, vertically stratifying foraging locations within pairs, increasing use of smaller trees for foraging, and possibly by using scrub habitats more extensively South Island saddlebacks appear to be highly adaptable in their choice of foraging sites and this plasticity may enhance the success of translocations.