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Sexing grey-faced petrels by discriminant analysis of measurements

Notornis, 39 (4), 261-265

R.M. Johnstone; B.E. Niven (1989)

Article Type: Paper

Discriminant function analysis was used to calculate classification formulae for predicting the sex of 98 adult grey-faced petrels (Pterodroma macroptera gouldi) at the start of incubation. Body weight, bill length, bill width, and bill depth all showed statistically significant sexual dimorphism. A classification formula based solely on bill measurements is impractical for sexing grey-faced petrels because of 37% error. The combination of body weight and bill depth in the formula proved useful, correctly classifying 92% of birds. This method provides a simple and reliable way of sexing grey-faced petrels in the field just after laying. Cloacal examination also allows definitive sexing at this time.

Effect of topography on seasonal distribution of forest birds in the Ohikanui, Lower Buller and Inangahua Valleys, North Westland

Notornis, 35 (3), 217-243

P.R. Wilson; R.H. Taylor; B.W. Thomas (1988)

Article Type: Paper

Birds were counted in the montane Ohikanui Valley and nearby at the mouth of the Buller Gorge in all four seasons of the year. Counts from these areas are compared with those from three sites previously studied in the much larger and broader Inangahua Valley in the same region. The effect of topographic temperature inversion on the deep and glaciated Ohikanui Valley is reflected in the pattern of vegetation and also in the altitudinal and spatial distribution of the birds. Large differences between the seasonal patterns of occurrence of some species of birds in the Ohikanui and Inangahua Valleys are demonstrated. Reasons for these differences are examined, such as seasonal migration in and out of the Ohikanui Valley for species such as tui (Prosthemadera novaeseelandiae), bellbird (Anthornis melanura), and silvereye (Zosterops lateralis) and altitudinal movement by species such as rifleman (Acanthisitta chloris) and grey warbler (Gerygone igata).  The study emphasises the importance of warm, floristically rich, lowland forest for the winter maintenance of honeyeater populations which breed in the montane valleys.

Clutch overlap by a New Zealand pigeon

Notornis, 35 (1), 59-62

M.N. Clout; P.D. Gaze; J.R. Hay (1988)

Article Type: Paper

The nesting behaviour of a New Zealand pigeon (Hemiphaga novaeseelandiae) fitted with a radio transmitter was closely monitored in lowland forest at Pelorus Bridge Scenic Reserve. The bird and its mate nested in January 1985, and a single chick fledged in early March. At least one week before this chick left the nest the radio-telemetered parent started incubation on a second nest c. 100 m away. This second nest, and a subsequent one in late March, failed because of disturbance by predators. Clutch overlap as a breeding tactic by New Zealand pigeons is discussed in relation to possible constraints on reproduction.

A re-examination of the moa genus Megalapteryx

Notornis, 35 (2), 99-108

T.H. Worthy (1988)

Article Type: Paper

A re-examination of the moa genus Megalapteryx reveals that the two currently accepted species, M. didinus (Owen) and M. benhami Archey, do not differ in the shape of the bones. They represent small and large specimens in an unbroken size continuum. Specimens from northwest Nelson have a larger mean size than those in a sample from Takahe Valley, Fiordland. A series of 14C dates indicates that the largest ‘M. benhami‘ are all of Otiran derivation, whereas M. didinus bones are from Otiran and Holocene deposits. Therefore M. benhami is synonymised with the upland moa, M. didinus (Owen).

Vocalisations of Procellaria petrels

Notornis, 35 (3), 169-183

J. Warham (1988)

Article Type: Paper

The vocal repertoires of grey, white-chinned, Parkinson’s and Westland petrels are compared with the aid of sonagrams. All species have some very loud calls built from short, staccato notes, often given at very high rates to produce rattles, cackles and brays. These appear to advertise the bird’s availability as a partner and/or possession of a territory, but some also seem to serve as threats. Other calls composed of longer notes are produced both when breathing in and when breathing out – as with Puffinus and Calonectris shearwaters. The recorded repertoire of the grey petrel is the smallest, that of the Westland petrel the most extensive. There are indications that in some species there are sexual differences in their calls, but experimental verification is needed to confirm this.

Size variation in the snow petrel Pagodroma nivea

Notornis, 35 (2), 109-116

S. Haftorn; F. Mehlum; C. Bech (1988)

Article Type: Paper

A colony of breeding snow petrels (Pagodroma nivea) in the Muhlig-Hofmann Mountains, Queen Maud Land, on the Antarctic continent was visited in January-February 1985. The birds were nesting under large boulders on the north-faced, ice-free hillside at Svarthamaren (71°53′ S, 5°10′ E), about 200 km from the open sea. The colony was roughly estimated to contain 500 pairs (Mehlum et al. 1985). Hatching took place in mid-January. The snow petrels at Svarthamaren were on average significantly smaller than those breeding elsewhere in the Antarctic. The irregular geographical distribution of breeding birds of varying size does not immediately provide any support for a sub-specific division of the species into one large and one small form, leaving the systematic and evolutionary status of the species unclear. It remains to be established whether inland breeding selects for relatively small birds.
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