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.
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.