Kiwi distribution in Northland was surveyed during 1992, largely by listening for calls. Kiwi were recorded at 242 sites in six Ecological Districts. High call rates were recorded in the central and northern parts of Northland in forest remnants of varying sizes, but remnants over 100 ha had significantly higher call counts. Kiwi have declined in abundance and range in southern Northland since the late 1970s. Threats and potential threats to Northland kiwi include habitat destruction and deterioration, but particularly predation by dogs and other introduced mammals.
Observations of birds were made while working on fishing trawlers intermittently for a total of almost a year in New Zealand subantarctic waters. Large numbers of several species of albatrosses and petrels are attracted to trawlers to scavenge and their numbers vary throughout the year. Species not attracted are seen less commonly. Scavenging behaviour around trawlers is discussed. There seems to have been an increase in scavenging by certain species in the last 30 years.
There are major sexual differences in the calls of Thin-billed Prion Pachyptila belcheti. This allowed birds to be sexed initially by calls, and then by their measurements. Males were on average larger than females for six out of eight morphometric characters, with the greatest difference being in the bill. We then investigated the possibility of sexing birds on the basis of external measurements: a discriminant function analysis based on the eight measurements allowed correct classification of 84.4% of the 281 birds. In 89% of breeding pairs, males had greater bill depth than their partner. A stepwise discriminant analysis revealed that bill depth, head length and body weight were the three most discriminant variables. The combinations of two measurements (bill depth and body weight, or bill depth and total head length) allowed correct classification of 84.3 and 83% of the birds respectively, whilst a classification solely based on bill depth gave a 83.2% correct classification. The degree of sexual dimorphism in this species is similar to that found in other tubenoses.
Kaka (Nestor meridionalis) less than one year old can be distinguished from older birds by a pale ring of skin around the eye (periophalmic ring). In birds less than five months old this has a yellow tinge, as does the cere, gape and the soles of the feet. A further distinguishing feature of Kaka between three and six months of age are protruding rachides (feather quills) on the tips of the tail feathers. On Kapiti and Little Barrier Islands, most Kaka nestlings fledge in February and receive food from their parents until June or July. Fledglings can often be detected during this period by their conspicuous and frequent food-begging behaviour. Juvenile characteristics in the Kaka persist for a much shorter period than in the Kea (N. notabilis), its sole extant congener. The loss of juvenile characteristics prior to sexual maturity suggests that juvenile Kaka becomes socially independent of adults earlier than Kea, presumably because of more readily obtainable food sources in their environment.
During a census in gardens in Hamilton, 71.8% of the 4428 birds observed belonged to introduced species. A total of 15 species were observed. Bird species richness was positively correlated with native plant biomass and, more strongly, with total plant biomass. More birds were present in gardens with more native plants. Among the most common species, the abundance of the House Sparrow (Passer domesticus) decreased with increasing percentage of native plants, the Silvereye (Zosterops lateralis) increased, while Blackbirds (Turdus merula) and Starlings (Sturnus vulgaris) showed no significant change. This was typical for a other introduced bird species. Most other birds, including the Fantail (Rhipidura fuliginosa) and the Grey Warbler (Gerygone igata), were most abundant in gardens with higher native plant biomass. Notable was the absence of the Tui (Prosthemadera novaeseelandiae) from all censused areas in Hamilton at the time of observation. No significant variation between morning and evening samples was noted.
Brown skuas (Catharacta skua lonnbergi) on rangatira (south east) and mangere islands in the chatham islands group were studied over a period of 14 years (1978/79 to 1992/93 breeding seasons) to determine factors promoting cooperative breeding in this population. The size and composition of the breeding population and overall breeding success were remarkably stable. No significant differences in breeding success, density of territories or periods of individual occupation in different places on these islands were demonstrated that would demarcate optimal and marginal breeding habitat. Neither could it be demonstrated that the islands were saturated by breeding birds as required for a habitat-forced origin of cooperative breeding.
The migration pattern of Cattle Egrets in 1990 and 1991 and its relation to meteorology are presented to extend initial results covering 1987-1989 (Maddock & Bridgman 1992). Cattle Egrets migrated to Victoria and Tasmania in waves during March and April in northerly air flow (western side of a high pressure system) in a series of stages, with periods of rest in between. Major staging points seemed to be Windsor (NSW), Nowra (NSW), and Baimsdale (Vic). Return migrations (October and November) appeared faster, with fewer and shorter rest stops, and were in southerly airflow. Staging points were Werribee (Vic), Nowra (NSW), and Wyong (NSW). Migrations to and from New Zealand were much more limited than in previous years due to adverse weather conditions, especially winds.
Records of Chatham Petrel (Pterodroma axillaris) up to 1989 are reviewed. A research programme that started in the breeding season of 1989/1990 to locate more individuals and more active burrows is described. Several methods of locating birds were employed and status of all burrows, and breeding success and measurements of all birds were recorded. The population at the end of the 1991/1992 breeding season is estimated. Conservation issues presented by the species are discussed.