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 fulua, Red-necked Stint Calidris rufcollis, 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.
During 1996, participants in the Beach Patrol Scheme patrolled 3071 km of the New Zealand coastline. There were 4649 dead seabids of 58 species recovered by patrollers. In addition, beach patrollers found 165 birds of 32 non-seabird species. Unusual finds included one Chatham Island Mollymawk (Diomedea cauta eremita), one New Caledonian Petrel (Pterodroma leucoptera caledonica), two Channel-billed Cuckoos (Scythrops novaehollandiae) and two Spine-tailed Swifts (Hirundapus caudacutus). There was a moderate-sized wreck of Sooty Shearwaters (Puffinus griseus) on North Island west coast beaches in November. The highest annual totals of Pitt Island Shag (Stictocarbo featherstoni) and Chatham Island Shag (Leucocarbo onslowi) were recorded in 1996. The mean annual recovery rates of Buller’s Mollymawks (Diomedea bulleri) and Black-billed Gull (Larus bullerti) were the highest recorded since the start of the Beach Patrol Scheme. Red-billed Gulls (Larus novaehollandiae scopulinus) had their lowest annual recovery rate in 1996. Causes of seabird mortality are discussed in the paper.
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 breeding biology of the North Island Tomtit (Petroica macrocephala toitoi) was studied at two sites in Pureora Forest Park, central North Island, during the 1997/98 season, and compared with data from the Ornithological Society of New Zealand’s Nest Record Scheme. The nesting season at Pureora was from 26 September 1997 to 15-17 February 1998, one pair fledging three broods. Of 11 Pureora nests and 32 of the Nest Record Scheme, 63.6% and 28.1% respectively were among dead hanging fronds of tree ferns, and 18.2% and 34.5% respectively were in holes in trees, rocks, banks, the ground or in nest boxes. The mean height of 11 nests at Pureora was 3.4 m, and that of 34 nests in the Nest Record Scheme was 2.8 m. Mean clutch size for the combined data was 4.15 eggs (n= 13). On all occasions, except one, females were incubating, with males feeding their mates at regular intervals. Both parents fed the chicks but only the female brooded them. Mean brood size at Pureora was 4.0 (n=4), but for the Nest Record card data it was 3.1 (n= 2 1). All 13 fledglings in four broods appeared to reach independence. Of 11 nesting attempts at Pureora, 72.7% were successful, compared with 45.4% of 11 attempts on Nest Record cards. This greater success at Pureora compared with other mainland areas was attributed to aerial 1080 possum control at Pureora reducing mammalian predator densities to low levels, and so reducing the incidence of predation.
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.
This paper describes the diet fed to chicks of two pairs of New Zealand Falcons nesting in forested habitat. Both pairs fed their chicks almost exclusively on birds weighing less than 85 g. No mammals or reptiles were recorded in the diet; invertebrates represented an insignificant component. Both pairs caught more medium-sized birds (20-35 g) than large (70-646 g) or small birds (5-14 g). Falcons showed no size-based selection; rather, the size of prey that falcons selected to feed to chicks closely matched their abundance. Sixteen species of birds were identified in the diet, and comprised 44% of the bird species present in the home ranges of both pairs. About half of the birds in the diet were introduced species.
From 13 to 18 December 1998, we counted Chatham Island Oystercatchers (Haematopus chathamensis) on approximately 310 km (96 – 97%) of the coastlines of Chatham, Pitt, Rangatira, and Mangere Islands, and 100 km (100%) of the shore of Te Whanga Lagoon, Chatham Island. A total of 142 adult Chatham Island Oystercatchers, including 34 confirmed breeding pairs and seven additional possible breeding pairs, was found. This is an increase of 20 to 40 adults over any previous count or estimate. Some of this increase may be due to efforts by the Department of Conservation to increase productivity of breeding pairs since the early 1990s along the northern coast of Chatham Island. Approximately 70% percent of the breeding pairs were on Chatham Island, 15% on Pitt Island, 10% on Rangatira and 5% on Mangere Island. Most of the oystercatchers (79% of individuals and 74% of the breeding pairs) were in areas we broadly defined as containing rocky wave-cut platform or other rocky coastline or outcrops. Thirty individuals and nine breeding pairs were on sandy beaches. One immature bird was on the shore of Te Whanga Lagoon.