Double-brooding has not previously been recorded in the New Zealand dotterel (Charadrius obscurus). Since 1994, we have recorded five definite cases of double- brooding in which both birds of the pair were colour-banded, two cases where banded females had unbanded mates, and several probable cases involving unbanded birds. In the five cases in which pairs were banded, females always re-nested with the same mate (monogamous double-brooding). We recorded one definite and one probable case of brood-overlap; in some other cases there was definitely no overlap. Predation, timing of laying, and individual variation are some of the factors that may determine whether double-brooding occurs in the New Zealand dotterel.
Breeding mohua (yellowhead, Mohoua ochrocephala; Passeriformes) have been intensively monitored in the Eglinton Valley, Fiordland, since 1990. Birds were individually colour-banded and their territories mapped. Trapping and poisoning stoats (Mustela erminea) resulted in a large increase in mohua numbers, but the population declined abruptly in winter 1996 following a period of unusually low temperatures. Details of the increase in numbers are presented and the reasons for the subsequent sharp population decline are discussed.
Population sizes and distribution of waders in New Zealand were determined for the first time during summer and winter, 1983-1994. In winter (June/early July), 163 000 New Zealand breeding and 21 000 Arctic migrant waders were recorded, and in summer (November/early December) 37 000 New Zealand breeding and 166 000 Arctic migrant waders were recorded. Species accounts, including seasonal totals for each year 1983-1994, average counts at favoured sites, and distribution maps are presented for the most abundant New Zealand breeding and Arctic migrant waders. The pied oystercatcher Haematopus ostralegus was the most abundant New Zealand breeding wader; the estimated winter total of over 112 000 birds showed that the population had increased by about 128% since 1970-71. Counts of pied stilt Himantopus himantopus (estimated winter total c. 28 000 birds) and banded dotterel Charadrius bicinctus (c. 11 000 birds) provided the first population estimates for these species during winter in New Zealand. However, both are significantly underestimated because many overwinter inland in sites not counted. Also, most of the banded dotterel population migrates to Australia following the breeding season. Wrybill Anarhynchus frontalis (c. 3900 birds) was next most abundant native species counted in winter, with most birds recorded in the North Island. Counts of spur-winged plover Vanellus miles, variable oystercatcher Haematopus unicolor, New Zealand dotterel Charadrius obscurus, black-fronted dotterel Charadrius melanops, and black stilt H. novaezelandiae also substantially underestimated population sizes because most birds of these species do not use estuarine sites during winter. During summer, bar-tailed godwit Limosa lapponica, lesser knot Calidris canutus, and turnstone Arenaria interpres were the most abundant of the Northern Hemisphere migrants with estimated populations of c. 102 000, 59 000 and 5100 birds, respectively, representing significant proportions of the East Asian-Australasian flyway populations of these species. Less than 700 birds were recorded during summer for each of the other Northern Hemisphere migrants, including (in decreasing order of abundance) Pacific golden plover Pluvialis fulva, red-necked stint Calidris ruficollis, whimbrel Numenius phaeopus, curlew sandpiper C. ferruginea, sharp-tailed sandpiper C. acuminata, and eastern curlew N. madagascariensis. Counts of uncommon Arctic migrants (i.e. those which reach New Zealand in most years) are also given.
Fifty-three captive-bred New Zealand shore plover (Thinornis novaeseelandiae) were released on Motuora Island in the Hauraki Gulf, New Zealand in an attempt to establish a second population of this endangered shorebird in the wild. The birds were liberated in four releases between September 1994 and February 1997. In September 1997, eight (15%) of the released birds were still resident on Motuora Island. Dispersal to the mainland was the principal known cause of loss of birds from the island, with predation being the next most important cause. Differences were found between the use of adult and juvenile birds for release but there did not seem to be any difference between using hand- or parent-reared birds. Possible seasonal patterns of disappearance may become clearer once more birds have been released on the island. Recommendations for future management and research include continuing the transfer programme to Motuora Island with intensive monitoring during the first month after release, inclusion of more adult birds in releases, release of both hand- and parent-reared captive birds and conducting more research into morepork predation of shore plover.
The diet of the morepork (Ninox novaeseelandiae) in New Zealand was investigated by analysing stomach contents. In the sample of 75 stomachs from throughout New Zealand, 1696 prey items were identified, 98% of them invertebrates. Major invertebrate prey taken included Lepidoptera, Coleoptera, and Orthoptera. Lepidoptera were consumed mostly in summer and Coleoptera in winter. Vertebrate prey were predominantly birds, but included one house mouse (Mus musculus). New dietary items included praying mantis (Dictyoptera), blowflies (Diptera), wasps (Hymenoptera), and slaters (Isopoda). Most prey was 20-50 mm in body length. Diets of male and female moreporks were similar, as were those of North and South Island birds. As suggested from other studies, the diet of moreporks is varied, but consists primarily of invertebrates. Food habits apparently reflect the seasonal abundance of prey.
Thirty-one species of wader have been counted on the Manukau Harbour and Firth of Thames in summer and winter censuses since the winter of 1960. Data are presented on total numbers of waders, the numbers of selected wader species and the numbers of observers involved in the counts. The numbers of many native waders have increased during the last 39 years, especially pied oystercatchers (Haematopus ostralegus), which have increased 8-fold from the 1960s to 1990s; however, pied stilts have been stable and wrybills (Anarhynchus frontalis) may be declining. Numbers of many Arctic wader species have increased on one or both harbours, but of the two main species, bar-tailed godwits (Limosa lapponica) have remained constant over both harbours and lesser knots (Calidris canutus) have declined slightly on the Firth of Thames but increased greatly on the Manukau Harbour. Notable changes of habitat are noted and possible reasons for changes in abundance of some species are discussed. Likely seasonal maxima of wader numbers are considered and the implications of these are discussed.
The diurnal and seasonal attendance of kea (Nestor notabilis) at Halpin Creek dump, Arthur’s Pass, from April 1996 to March 1997 was investigated. Many more male (n=56) than female (n=4) kea were banded at the dump. Resighting data suggested that certain adult male kea habitually foraged at the dump, whereas younger male kea probably foraged at the dump until they dispersed from the dump in their second summer. The time individual kea spent at the dump varied considerably within and between seasons, but did not depend on the individual’s age. More kea were observed at the dump in winter than in summer and they spent more time at the dump in the winter than in summer.
In the mid-19th century, the southern subspecies of the New Zealand dotterel (Charadrius obscurus obscurus) was widespread in the South Island of New Zealand. It now no longer breeds there and the only recent records are coastal; these are of juvenile and unpaired birds wandering from the small relict population on Stewart Island. Written records and data from museum specimens collected before 1940 are presented, and possible causes of the decline are discussed. The records tend to confirm earlier suggestions that the southern subspecies bred inland. The available evidence suggests that the species had declined in the South Island by the early 1880s. Predation by feral cats (Felis catus) and possibly Norway rats (Rattus norvegicus), and shooting were the most likely causes. During the period 1880-1900, the decline appears to have become more rapid, coinciding with the introduction and rapid spread of mustelids (Mustela spp.) in the mid-late 1880s. The last specimen that may have been a breeding bird was collected in or before 1903. Cats, rats and mustelids were also introduced to the North Island but the northern New Zealand dotterel (C. o. aquilonius) has survived there; possible reasons for this difference are discussed.
The identification of predators from prey remains is dependent on predators leaving distinctive sign. Captive moreporks (Ninox novaeseelandiae) were fed birds and birds’ eggs and the remains were examined for distinctive features. Moreporks left distinctive feeding sign; severing wing feather shafts and removed wing feathers from birds. Predator feeding sign can aid bird conservation by providing strong circumstantial evidence of predator identity.
Caspian terns (Sterna caspia) from an isolated colony in southern New Zealand were studied for 30 years. Aims of the study were to identify the birds’ wintering grounds and to discover the whereabouts of birds during immaturity, by tracing movements of known-aged birds. Adults moved to several wintering grounds up to 1150 km to the northeast. Some birds were locally nomadic in winter, but little distance nomadism was identified in adults. In some families, one parent left the colony up to three weeks before the rest of the family. Juveniles left their natal colony when aged 7–9 weeks, and each was accompanied by one parent until aged 8–9 months. Typically, parents took turns at accompanying a juvenile, in stints of ca. 1-3 days, but two siblings wintered 360 km apart, each accompanied by a parent. Birds on outward passage moved in stages in flocks of 2–4 birds. Families lingered at staging areas for 2-26 days. A 49–54 day old juvenile moved 195 km in five days. Mortality was high in juveniles which moved further than ca. 900 km. Seventy seven percent of juveniles remained sedentary at their wintering ground to age 9 months, and 30% stayed on at the same location through their second winter. Immature birds remained sedentary, were locally nomadic or wandered far inland. Some returned to the colony and stayed briefly, but those which had wandered tended to remain at one site for weeks or months before moving on. Juveniles begged only from their parents. Flight skills and some feeding behaviour of known-aged juveniles are described, as are some behaviours at staging areas.
Aerial surveys for flying seabirds were directed up to 18.3 km offshore from Banks Peninsula during February and July-August 1996. The abundance of Hutton’s/fluttering shearwaters (Puffinus huttoni/P. gavia) increased offshore, consistent with possible offshore increases in pelagic versus benthic productivity The decrease in abundance offshore of spotted/pied shags (Stictocarbo punctatus/Phalacrocorax varius), black-backed gulls (Larus dominicanus), white-fronted terns (Sterna striata), and red-billed/ black-billed gulls (L. novaehollandiae/L. bulleri) probably reflects their commuting to and from breeding and roosting sites. Hutton’s/fluttering shearwaters and white-fronted terns were most common around the area east of Banks Peninsula. The distribution of other species around Banks Peninsula probably reflects breeding site distribution (spotted shags), and feeding opportunities on land (black-backed gulls). Convergent fronts were distributed around Banks Peninsula, and decreased in number offshore. Internal waves were most common toward the eastern end of Banks Peninsula, and were evenly distributed offshore. While the onshore-offshore distribution of the non- procellariiform species matched that of convergent fronts, seabirds and individual convergent fronts did not significantly co-occur.
Uncertainty still surrounds the status of the orange-fronted parakeet, Cyanoramphus malherbi. Doubts first raised in 1974 that it was merely a colour morph of the much more common yellow-crowned parakeet, C. auriceps, were supported by a morphometric study of museum specimens in 1981, and the results of cross-breeding experiments with wild-caught and aviary birds in 1986. Subsequently, the orange-fronted parakeet was deleted from the most recent Checklist of the Birds of New Zealand. However, some researchers and conservation managers remain unconvinced, because of doubts raised by electrophoresis of blood proteins, and claimed differences in the orange-fronted bird’s size, behaviour and ecology. This paper reviews the topic, discusses the evidence and arguments in the species versus colour morph controversy, and supports the view that the 2 forms are colour morphs of a single species.