The eastern shore of Lake Wairarapa is a nationally important site for waders. The monthly distributions of eleven species of wader and of White-faced Herons (Ardea novaehollandiae) are presented from monthly counts between November 1983 and October 1994. Numbers of Spur-winged Plovers (Vanellus miles) increased dramatically during this period. Water levels in this shallow freshwater lake vary with regional rainfall, the management of floodgates at the outlet of the lake, and wind direction and strength. Numbers of Pied Stilt (Himantopus himantopus), Banded Dotterel (Charadrius bicinctus) and Black- fronted Dotterel (C. melanops), for which the lake is an important wintering site, declined once the water level rose over about 10.3 m above an imaginary reference point (datum), and also declined below about 9.95 m above datum. Our findings confirm the importance of managing lake levels and we discuss how these data were used in setting operating levels for a water right application to operate the floodgates at the outlet of the lake.
Population trends in the Western Weka (Gallirallus australis australis) in Golden Bay and the Marlborough Sounds were examined by field surveys and reference to the literature. Weka declined on the southern margin of Kenepuru Sound in 1995-96, but they were still at 0.10 and 0.06 ha-1 at Big Bay, Endeavour Inlet, and Long Bay near St. Omer, respectively.Weka numbers have declined in lowland Golden Bay to less than 0.01 ha-1 since 1986. The reasons for this declines is unknown, but it appears that high densities of mustelids peaks and climatic extremes are times when Weka populations need close monitoring.
Snares Island Snipe (Coenocorypha aucklandica huegeli) were studied on the Snares Islands during parts of six breeding seasons between 1982 and 1987. Laying was between 4 November and 19 February; the breeding season (including chick-rearing) spanned the months November to May. Nests were well concealed among dense vegetation with solid overhead cover. Most birds were monogamous, with shared incubation of the two-egg clutch. Males incubated for 51% of the time, mainly at night and during late afternoon; females incubated 49% of the time, mainly during the morning and early afternoon. The eggs hatched synchronously and the chicks stayed in the nest for less than 13 h. The male cared for the first chick to leave the nest. Growth of chicks is described using Gompertz equations. Full juvenile plumage took c. 54 days to attain, and adult size in all growth parameters was attained soon after independence (c. 65 days).Chatham Island Snipe (C. pusilla) were studied on Rangatira Island during the 1983-84 breeding season. Laying was estimated to extend from late September to the end of December. Most nests found (86%) were under Carex sedges. Incubation of the two-egg clutch was shared; incubation patterns were not determined. The eggs were 19% smaller in relation to predicted egg-weight than those of Snares Island Snipe. The eggs hatched synchronously and the chicks stayed in the nest for less than 11.5 h. The male cared for the first chick to leave the nest. Full juvenile plumage took c. 47 days to attain. The bill grew much more rapidly than for Snares Island Snipe and chicks became independent much earlier (c. 41 days old).
The growth of New Zealand’s second mainland Australasian gannet (Morus serrator) colony at Muriwai, north west Auckland is described from counts between 1975 and 1998. The colonies on Motutara Island, and the southern and northern colonies on Otakamiro Point have increased from 28 pairs in 1975 to 1393 pairs in 1998. The potential for future colony expansion on the northern cliff face, where human disturbance is highest, is discussed.
We observed that South Polar Skuas (Catharacta maccormicki) breeding near the Adelie Penguin (Pygoscelis adeliae) western colony at Cape Crozier, Ross Island, Antarctica were able to forage throughout the colony, the majority of which was not defended by territorial skuas as in other Ross Island colonies. All local skuas were able to find enough food on the colony throughout January to support breeding and none were seen to forage at sea. Skuas foraged as individuals to obtain penguin eggs and chicks but kleptoparasitism usually occurred so that several skuas fed in turn on a single carcass. At the end of each feeding event a general melee occurred in which up to 30 skuas fought over the chick remains. The implications for skua breeding of this foraging regime, in which any skuas in the local area can obtain penguin food, are considered. We suggest that the high levels of food availability contributed to the unusually high success for this region of these skuas in raising both chicks. Desertion of chicks while foraging, however, leads to some mortality among older chicks later in the season through predation. It is recommended that further research on skuas at super-large penguin colonies be undertaken.
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 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.