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.
Between 1979 and 1998, 6975 Arctic waders of seven species (mainly lesser knots Calidris canutus and bar-tailed godwits Limosa lapponica) were caught by the Miranda Banders and the New Zealand Wader Study Group near Auckland. Of these, 1375 were marked with a white leg-flag on the tibia to denote capture in New Zealand. Thirty-two lesser knots and three bar-tailed godwits had already been banded overseas, mainly in Australia. Another two lesser knots and two bar-tailed godwits banded overseas have been found dead in New Zealand. Up to 135 lesser knots, 34 bar-tailed godwits, 2 turnstones and 2 red-necked stints (Calidris ruficollis) bearing Australian leg-flags, and 2 colour-banded bar-tailed godwits from Alaska have been seen in New Zealand. Of those birds banded or leg-flagged in New Zealand, up to 21 lesser knots, up to 17 bar-tailed godwits, and two turnstones (Arenaria interpres) have been recovered or seen in six overseas countries. One turnstone banded in New Zealand was caught in Australia and then recaptured back at its original banding site. The migration routes taken by lesser knots, bar-tailed godwits and turnstones visiting New Zealand have been deduced from these band recovery data.
The sediment ponds and tidal flats at Port of Whangarei have been significant roost areas for waders since they were created from dredge tailing in the late 1960s. In 1971, 11 species of waders fed or roosted in this area; New Zealand dotterel (Charadrius obscurus), white-fronted tern (Sterna striata), Caspian tern (S. caspia) and black-backed gull (Larus dominicanus) bred there, and on six islands of mud and shell. Intensive observation in 1979-80 and 1995-98 found that the residency status of many species had changed. There were significant declines in the numbers of New Zealand dotterel, Caspian tern and skylark (Alauda arvensis), and significant increases in the numbers of red-billed gull (L. novaehollandiae scopulinus) and house sparrow (Passer domesticus). These changes were associated with development of sedimentation ponds and increases in weed-stabilised communities and cover by mangroves. Future bird use of this area is very dependent on the management of the ponds, and the rate of encroachment of mangroves or ponds over the main mudflat roost area. A new island would safeguard wader roosting in the upper harbour.
Lesser knots (Calidris canutus) are high-Arctic breeding waders that migrate to temperate and tropical regions for the non-breeding season. Seasonal mass changes were examined in lesser knots in New Zealand at the southern end of their migration. Adults showed a large increase in mass in February before their northward migration in March. They were estimated to depart with a ‘fat’ load of around 45%. Subadult birds, most of which winter in New Zealand over the northern breeding season, also showed a mass increase. Mass increases in winter are well documented for European waders but contrary to the European situation, this increase in subadult birds in New Zealand is unlikely to be an adaptive strategy to insure against periods of negative energy balance. Instead, it may be an endogenously orchestrated byproduct that has not been selected against in the pre-migratory period. Such increases may be more widespread in Arctic waders in the Southern Hemisphere than is realised.
The nesting activities and breeding success of black shags (Phalacrocorax carbo) near Lake Kohangatera, Wellington, were studied from 1993 to 1998. The colony was used during November-July by a mean of 67 birds per night, but in August-October numbers increased to a mean of 98 birds when fledglings were present. Courtship and nest-building began in March, and nesting continued until October-November when the last chicks fledged. Most clutches (85% of 185) were laid in April-May (early nests), the remainder being laid in June-September (late nests). The mean estimated laying date of early nests varied from 14 April in 1998 to 3 May in 1995, the overall mean (1993-98) being 24 April. During the day typically the male took two incubation stints, including the first, and the female one or two. The mean length of incubation stints by females was 3 h 46 min, over an hour longer than that of males. However, the mean time females and males were absent from the colony to forage, 2 h 39 mins and 2 h 21 mins respectively, did not differ significantly. Three types of changeovers seen during incubation are described, as are the activities of adults and chicks during nestling rearing. Fledglings took their first flights when 49-60 days old, but continued to be fed by their parents for 40 to 80 days afterwards, the oldest fledged young seen fed being about 140 days old. Of 185 breeding attempts during 1993-98, 83% were successful, the majority resulting in one or two fledglings per nest. Mean brood size at fledging varied with year, from 1.1 in 1997 to 1.7 in 1998. Overall, the mean brood size was 1.4 fledged young per nest, and 1.7 for successful attempts. Early clutches were more productive than late ones. We conclude that a pair of black shags would be unable to successfully rear two broods and complete their moult within a year, and that late nestings were replacement clutches.