Since its recent arrival in New Zealand the Black-fronted Dotterel (Charadrius melanops) has begun winter flocking, and a newly observed feeding technique has become common. This new feeding behaviour is used mainly on hard substrate. The bird taps the substrate before pecking at prey, and on hard substrate the
capture rate is higher than by simple pecking. By imitating the tapping on soft, intermediate and hard surfaces, I found that vibrations from the tapping on hard substrate alone caused flies to jump, making them more visible.
In winter, birds were heard calling an hour before sunrise as they flew from sleeping sites scattered along the Manawatu River to the sludge ponds at the freezing works. The dotterels returned to the river after several hours of feeding but again visited the sludge ponds from mid-afternoon to almost an hour after sunset. At both the river and the sludge ponds most prey consisted of two species of fly. Daily time budgets showed that birds were feeding for 38% of the day while incubating, 69% while tending chicks and 86% during a winter’s day. It was estimated that during a winter’s day, one apparently normal bird caught 28,737 insects. To do this it pecked at 31,579 insects and caught one insect every 1.5 seconds.
The breeding of Banded Dotterels (Charadrius bicinctus) was studied in 1977-1987 at Cass River Delta, Lake Tekapo. Most birds first nested as 1-year-olds, but 1-year-olds arrived later on the breeding grounds than experienced adults. Nest site fidelity between years was high for experienced males but less for experienced females. Natal site fidelity was lower in females, which nested up to 31 km from the natal site. The birds were monogamous and usually retained the same mate for repeat clutches within a season, but most changed mates between years. Family members parted at about the time the young could By. Sight recoveries of juveniles indicated that those which had fledged early or midway through the season subsequently migrated to Australia bur late fledging juveniles were non-migratory.
A new species of extinct starling, Aplonis diluvialis, is described from the Fa’ahia Archaeological Site on Huahine, Society Islands, French Polynesia. A. diluvialis was larger than any Indo-Pacific congeners except A. atrifusca of Samoa. The only other Eastern Polynesian islands where starlings have been recorded with certainty are Rarotonga (A. cinerascens) and Mauke (A. mavornata). In pre-human times, however, species of Aplonis may have occurred through much of Eastern Polynesia.
Discriminant function analysis was used to calculate classification formulae for predicting the sex of 98 adult Grey-faced Petrels (Pterodroma macroptera gouldi) at the start of incubation. Body weight, bill length, bill width, and bill depth all showed statistically significant sexual dimorphism. A classification formula based solely on bill measurements is impractical for sexing Grey-faced Petrels because of 37% error. The combination of body weight and bill depth in the formula proved useful, correctly classifying 92% of birds. This method provides a simple and reliable way of sexing Grey-faced Petrels in the field just after laying. Cloacal examination also allows definitive sexing at this time.
Cavity nesting by Stitchbirds (Notiomystis cincta) was studied on Little Barrier Island by adding artificial nest sites (boxes) in a breeding habitat. The addition of boxes was a test of the theory that the number of breeding pairs of cavity nesting species is limited by the availability of suitable holes for nest sites. Site limitation is also said to prevent males of these species from taking more than one mate. This theory was tested by placing some boxes close to natural nest sites and other boxes. Results showed that the number of breeding Stitchbirds was not necessarily limited by the availability of sites, and that lack of sites did not restrict male birds to monogamy. The boxes could be a useful management tool for enhancing this rare species.
The effect of wind and sea conditions on the feeding of Antarctic Terns (Sterna vittata bethunei) was studied during three visits to the Snares Islands. The terns preyed upon fish and swarms of crustaceans. Increasing wind speed significantly reduced the terns’ capture rate and feeding success. The terns fed in similar ways with calm and moderate seas. However, rough seas significantly reduced the attempt rare, capture rate, and feeding success of terns feeding on fish and the capture rate and success of terns feeding on crustaceans. Foraging techniques varied with the type of prey sought and
sea conditions. To catch fish, the terns mostly plunge dived in calm seas but contact dipped for 40-46% of attempts in moderate and rough seas. They caught crustaceans mainly by contact dipping, but used partial plunge diving more in moderate and rough seas. Wind speed and sea conditions seemed to affect terns feeding on crustaceans by making prey move away from the surface. Several other species of seabirds joined the terns to feed on crustacean swarms. Interspecific interactions were minor; however, large flocks of Sooty Shearwaters (Puffinus griseus) displaced terns from feeding on swarms.
From April 1987 to April 1988 (inclusive) I completed 195 5-min stationary bird counts at two forested sires in the Auckland City Domain. Auckland Domain has 22 species of passerines and near-passerines, more than half of them introduced. The mean annual counts – the first published for the North Island – showed a very high incidence of Silvereyes, Blackbirds and Fantails compared
with beech-podocarp forests and conifer plantations of the northern South Island, and a low incidence of Grey Warblers and Shining Cuckoos. Whether these are general characteristics of northern or urban forests awaits further study.