Since the first burrows of Chatham Island Taiko Pterodroma magentae were found in 1987/88, trapping around the burrows has killed 204 feral cats Felis cattus, 3053 Possums Trichosurus vulpecula, 1572 Weka Gallirallus australis and 589 rats Rattus spp. in 109,892 trap-nights to March 1993. No Taiko are known to have been killed by predators. Productivity was static at one fledgling per year until 1992/93, when two fledglings were reared. Unobtrusive studies of breeding biology indicated that mating occurred about 1 October, laying about 26 November, hatching about 20 January and fledglings departed about 4 May. The pre-laying exodus of females lasted up to 50 + days and chick-rearing took about 105 days.
The Incredible KiwiKiwis. A Monograph of the family ApterygidaeKiwi – A Secret LifeHandbook of Australian, New Zealand & Antarctic Birds. Vol I, Ratites to Ducks
Forest of several types covered 45.14% of South East Island, Chatham Islands (218 ha). All petrel burrows in 200 10 m2-quadrats in modified and unmodified forest were counted during breeding seasons in 1989 and 1990. From the total of 2675 burrows (1.338 burrows m-2 of forest), we estimated a breeding seabird population of more than 1.3 million pairs. The main species were White-faced Storm Petrels (Pelagodroma marina) (840,000 pairs), Broad- billed Prions (Pachyptila vittata) (330,000 pairs), and Southern Diving Petrels (Pelecanoides urinatrix) (127,000 pairs). Smaller numbers of Sooty Shearwaters (Puffinus griseus), Grey-backed Storm Petrels (Oceanites nereis) and Chatham Petrels (Pterodroma axillaris) also bred in the forests. Comparisons are made with population estimates for other New Zealand islands, parts of the Galapagos Islands, Baccalieu Island (Newfoundland), and the Juan Fernandez group. Conservation issues for South East Island are discussed.
The carpometacarpus of the extinct, flightless gruiform Apterornis is described and illustrated, based on one specimen from the North Island form (A. otidiformis) and two specimens from the larger South Island form (A. defossor). The element is uniquely truncated distally, resulting in the loss of the distal portions of ossa metacarpalia majus and minus, the entire extremitas distalis carpometacarpi, and the spatium intermetacarpale. Although a few features of the extremitas proximalis carpometacarpi are variably discernable (e.g., trochlea carpalis, fovea carpalis cranialis, and fossa supratrochlearis), most features typical of the element in other Gruiformes are lacking. In both specimens for A. defossor, phalanx digiti alulae is synostotic with processus extensorius of the carpometacarpus, whereas in the single specimen for A. oridiformis the phalanx is absent. The absence of facies anicularis of phalanges digiti majoris and digiti minoris indicates the loss of both digits in Apterornis. The qualitative, flightlessness-related apomorphies of the carpometacarpus of Apterornis are unique among birds, and indicate a degree of alar reduction unequalled among carinate birds.
Fossil bones and earlier observations indicate that up to 22 species of bird have become extinct on Mangere Island. The extinctions appear to have been primarily a result of predation by cats, but human hunting and bush clearance are likely to account for the disappearance of some species. A crested penguin Eudyptes ?n.sp., two species of Pterodroma petrel, a shelduck Tadorna ?n.sp., Dieffenbach’s Rail Gallirallus dieffenbachii, and a kaka Nestor ?n.sp. are present in fossil deposits on Mangere Island, but have not been reported from the island before. The relative proportion of remains in the deposits suggest that Blue Penguins Eudyptula minor, Broad-billed Prions Pachyptila vittata and Sooty Shearwaters Puffinus griseus have become more common on the island. Any such increases on Mangere Island, could have been a response of a few species to the large decrease in numbers and diversity that has affected seabirds as a whole at the Chathams. Some seabird species may have been able to increase because of reduced competition for food.
Archaeological and palaeontological excavations were conducted as part of the Pitcairn Islands Scientific Expedition (January 1991 to March 1992). In this preliminary analysis of the subfossil bird bones from Henderson Island (24022( S, 12S018( E) we identified 29 taxa, which were divided into five groups: (1) four endemic extinctions, (2) five local extinctions, (3) a minimum of 12 breeding residents, (4) three non-breeding migrants, and (5) five birds of uncertain status. Over half of the landbird species known from Henderson Island are listed here for the first time, including one new genus and at least three new species. New listings for Henderson Island include: Henderson Archaic Pigeon (Columbidae new genus), Henderson Ducula Pigeon (Ducula new species), Henderson Ground-Dove (Gallicolumba new species), Henderson Sandpiper (Prosobonia new species), Royal Albatross, Little/Audubon’s Shearwater, Bulwer’s Petrel, Black-winged Petrel, Sooty Tern, cuckoo (Eudynamys sp.), and a swallow (Hirundo sp.). Most of the bird bones collected were associated with prehistoric Polynesian occupation sites dating from ca. AD 1000 to 1600. Humans may have caused the extinction of at least four of the eight endemic landbirds, which equates with similar extinction rates on other Pacific islands.
The New Zealand Shore Plover Thinornis novaeseelandiae is colourful and sexually dimorphic, which is unusual among plovers. T. novaeseelandiae is confined to Rangatira (South East Island) in the Chatham Islands. The sedentary population is relict. The mainland New Zealand population declined over the past century, probably as a result of predation by introduced rodents and feral cats. The population of about 130 birds includes 43 or 44 breeding pairs. There is no migration or dispersal from Rangatira. The population has been stable at least since 1969, but could increase by 12% per annum. Shore plover are long-lived. Survival and productivity are age- dependent. Mortality was highest among juveniles and for all birds in winter. Compared to other shore birds, adult mortality is low, and productivity high. The high proportion (20-35%) of non-breeding adults suggests that population increase may be constrained by a shortage of suitable habitat. Although the population appears to be stable at present, a single small population of a species is always in danger of extinction. A recovery programme now under way is aimed at establishing new populations.