We report Records Appraisal Committee (RAC) decisions regarding Unusual Bird Reports received between 1 Aug 2008 and 31 Dec 2010. Among the 58 submissions accepted by the RAC are the 1st New Zealand records of streaked shearwater (Calonectris leucomelas) and straw-necked ibis (Threskiornis spinicollis), 2nd records of great shearwater (Puffinus gravis), semipalmated plover (Charadrius semipalmatus) and Franklin’s gull (Larus pipixcan), and 3rd records of little stint (Calidris minuta) and black kite (Milvus migrans). Other notable records included the 1st oriental cuckoo (Cuculus optatus) from the Kermadec Islands, a New Zealand dabchick (Poliocephalus rufopectus) near Nelson, and 2 records of Stewart Island shag (Leucocarbo chalconotus) near Lake Ellesmere, Canterbury.
We investigated the population size and annual survival of Salvin’s albatrosses (Thalassarche salvini) breeding at the Western Chain, The Snares, New Zealand. A count of breeding pairs during incubation resulted in totals of 1100-1200 breeding annually on Toru and Rima Islets in the 3 years 2008-2010; none was seen breeding on Tahi, Rua or Wha Islets. The majority of adults bred annually. Based on banding and recapture the annual survival probability of breeding birds was estimated to be 0.967 while that of known-age birds banded as chicks in Feb 1986 was estimated at 0.939. A bird banded as a chick on the Bounty Is in 1985 was found breeding on Toru Islet of the Western Chain in the 3 years 2008-2010. This is the first record of a banded Salvin’s albatross breeding away from its natal island.
Home range size, travel distances, and population density of the great spotted kiwi (Apteryx haastii) were investigated in the North Branch of the Hurunui River. Radio tracking was conducted on 10 great spotted kiwi between Dec 2007 and Apr 2008. The estimated minimum home-range sizes were determined using the concave polygon method and ranged between 19.6 ha and 35.4 ha, with a mean of 29.3 ha (± 1.6 SEM). The observed nightly distances travelled per hour varied from 7 to 433 m (n = 569). Most estimates of travel distances (73%) were clustered in the classes from 0 – 150 m/hour, and distances over 200 m/hour were seldom achieved (only c. 7% of distances). The kiwi population in the Mainland Island site on the western North Branch of the Hurunui River was estimated to hold around 290 birds in total. Population density for the entire North Branch area was estimated to be 2 pairs/km² and when including subadults, 5 birds/km². Our estimate of home range size is larger but with more variation than found in other studies. Differences in population density estimates between our study and those in the Hurunui and Arthurs Pass district may be due to different objectives and methods.
Population size and breeding success of northern New Zealand dotterels (Charadrius obscurus aquilonius) were studied on the recently mammalian predator-eradicated Motuihe Island in the Hauraki Gulf, New Zealand. The island’s entire breeding population was monitored during the austral breeding season from Nov 2007 – Feb 2008. Nine breeding pairs were identified and their breeding success recorded. A total of 41% of nesting attempts produced fledglings and 1.22 chicks fledged per pair for the season; each egg had a 38% chance of survival to fledging. The breeding success of this endemic shorebird was twice as high on Motuihe Island as that at unmanaged mainland sites, and is comparable to levels of breeding success at other managed sites with mammal trapping or predator-proof fencing. The only identified cause of nesting failure over the breeding season was avian predation. Suggestions are made to maintain and enhance breeding success at this locality.
Prey remains and regurgitated pellets of New Zealand falcons Falco novaeseelandiae, from Adams I in the Auckland Is, were collected to determine the diet of this species in the subantarctic part of their range. Dissection of pellets revealed 1588 bones from 215 individuals of 18 species of birds preyed upon. Feathers associated with the remains supported the bone identifications. Rangle stones were also collected. The presence of procellariiform seabirds in the diet of falcons suggests some nocturnal hunting. While the single most frequent prey species was the bellbird (Anthornis melanura), Antarctic prion (Pachyptila desolata) and subantarctic diving petrel (Pelecanoides urinatrix exsul) were also common. When measured by prey weight, endemic land birds such as Auckland I rail (Lewinia muelleri), Auckland I snipe (Coenocorypha aucklandica aucklandica), and Auckland I teal (Anas aucklandica) constituted a third of the prey. Like many island birds, these ground-dwelling species cannot co-exist with introduced mammalian predators, but survive despite predation by native falcons.
The North Island robin (Petroica longipes) was introduced to the Zealandia – Karori Sanctuary in 2001. The sanctuary is a mainland island (225 ha) in Wellington that is free from all mammalian predators except mice (Mus musculus), and enclosed by a predator-proof fence. During 2001 and 2002 a total of 76 robins were translocated from Kapiti I to the sanctuary. To assess changes in this population since its introduction, I surveyed and mapped territories of robins in a 37 ha section of the sanctuary in 2008. Density has continued to increase, from 0.7 robins/ha in 2003 to 2.5 robins/ha in 2008. This density is higher than other mainland sites. Of 46 adult robins seen within the study area at the start of the 2004-05 breeding season, at least 17 remained within the area in 2008, close to their 2004 territories. These included 4 robins from the original transfer. In all cases where both partners from 2004 were seen in the study area in 2008, the pair bond remained intact. My survey confirms continued increase in this introduced population and high pair fidelity.