Breeding of pied shags (Phalacrocorax varius) at 2 colonies at Makara Beach, Wellington, was studied from Mar 1996, when breeding was 1st noted there, to May 2005. Pairs occupied and refurbished vacant nests rather than build new nests. The number of breeding attempts increased from 3 in 1996 to 46 in 2004, with 166 occurring during the study. New nests (n = 14) took about 3 weeks to build; most nests were used twice a year. Clutches were laid in all months, but there were 2 peaks: 61 nests (37%) in Feb–Mar and 53 nests (32%) in Aug–Sep. Overall, 76.6% were successful (fledged at least 1 nestling, n = 154 breeding attempts for which the outcomes were known), and the mean success was 1.4 fledglings nest-1. The proportion of successful breeding attempts and the mean number of fledglings produced nest-1 were similar for 1996-2000 (when the number of breeding attempts yr-1 increased from 3 to 11) compared with the 2001-2005 period (when breeding attempts increased from 15 to 46 yr-1). Of 14 breeding attempts for which clutch size was determined, mean clutch size was 3.4 (range 2-4 eggs), and mean brood size at fledging was 2.1 young (62% of eggs resulted in fledglings). The maximum number of shags counted at the colonies increased from 14 in 1996 to 68 in Dec 2003, after which numbers appeared to stabilize. However, since 2003, numbers of pied shags seen elsewhere in the Wellington region, particularly on Mana I and at Waikanae Estuary, have increased.
An appraisal of the conservation status of the post-1800 New Zealand avifauna is presented. The list comprises 428 taxa in the following categories: ‘Extinct’ 20, ‘Threatened’ 77 (comprising 24 ‘Nationally Critical’, 15 ‘Nationally Endangered’, 38 ‘Nationally Vulnerable’), ‘At Risk’ 93 (comprising 18 ‘Declining’, 10 ‘Recovering’, 17 ‘Relict’, 48 ‘Naturally Uncommon’), ‘Not Threatened’ (native and resident) 36, ‘Coloniser’ 8, ‘Migrant’ 27, ‘Vagrant’ 130, and ‘Introduced and Naturalised’ 36. One species was assessed as ‘Data Deficient’. The list uses the New Zealand Threat Classification System, which provides greater resolution of naturally uncommon taxa typical of insular environments than the IUCN threat ranking system. New Zealand taxa are here ranked at subspecies level, and in some cases population level, when populations are judged to be potentially taxonomically distinct on the basis of genetic data or morphological observations. In contrast, IUCN and BirdLife International bird threat rankings are assigned only at species level. This paper represents the first time that the entire modern New Zealand avifauna has been assessed from a conservation perspective. A brief analysis of patterns of extinction, threat, and rarity exhibited by the taxa listed is presented.
The New Zealand storm-petrel Pealeornis maoriana Mathews, 1932 was described from 3 specimens collected in the 19th century. Since 1952 it has most commonly been considered a subspecies of Wilson’s storm-petrel Oceanites oceanicus exhibiting the ventrally streaked “Pealea” phenomenon. There had been no recorded sightings of the New Zealand storm-petrel in over 170 years before Jan 2003. Since then, observations off northern New Zealand of storm petrels believed to be this taxon have been made regularly during the austral summer. From observations and photographs, these birds appeared more similar to the New Zealand storm-petrel than to other storm petrel species occurring in the region. However, confirmation of their identity was not possible without capture. In Nov 2005 one was captured off Little Barrier Is, and 3 more were caught elsewhere in the Hauraki Gulf in Jan 2006. Analyses of detailed descriptions, photographs, and morphometric data of these birds provide conclusive evidence that they represent an extant population of the New Zealand storm-petrel. Our analyses of these data and comparison with the New Zealand storm-petrel museum specimens and 17 other Southern Hemisphere storm petrel taxa (subfamily Oceanitinae), lead us to conclude that this species is distinct.
Motuora is a highly modified island in the Hauraki Gulf that is currently being re-vegetated. It is envisaged that the island will eventually be restored to a native forest system with strong seabird influences. The island retains a small breeding population of grey-faced petrels (Pterodroma macroptera gouldi). In 2005 a survey of the accessible areas of the coastal margin was carried out to estimate the current size of the population. The survey located 406 active burrows and it was estimated that approximately 260-280 burrows contained incubating pairs. There was some evidence that active burrow numbers had increased at established breeding areas since the last survey in 1995, but differences between survey methods made comparisons difficult. Fixed monitoring plots were put in place in 2005 to provide a standardized measure of changes in burrow activity. Between 2005 and 2007 no change in the number of active burrows was discernible in the fixed plots. Longer term monitoring will be required to determine the population dynamics of the Motuora grey-faced petrels as evidence from other locations indicates that growth (if it occurs) will be slow. Consequently, seabird numbers (and associated nutrient inputs) on Motuora are likely to be below pre-disturbance levels for many decades. These results highlight the challenges of ecosystem restoration in highly modified habitats.