The kakapo (Strigops habroptilus) is a nocturnal, herbivorous parrot that shows lek behaviour and does not breed every year. When breeding does occur, egg-laying and incubation in mid-summer are followed by a prolonged period of chick-rearing, with all parental care provided by the female. Breeding years for kakapo are associated with mast seeding years for a range of forest trees and plants, and the periodicity of kakapo breeding is linked with the periodicity of years of large seed and fruit production by their major plant foods. Kakapo are likely to have an annual cycle of gonadal growth and regression driven by the annual cycle of day length, with breeding occurring in years when kakapo respond to cues from a range of plant species that undergo masting. Kakapo breeding is initiated in response to cues that appear in early summer, but in some years there is insufficient food for the rearing of young in the following autumn. Rimu (Dacrydium cupressinum) is an important food source for chick rearing and is likely to provide an important cue for kakapo in areas where rimu is present.
Between 1992 and 2002, the 4 main colonies of the king shag (Leucocarbo carunculatus) in the outer Marlborough Sounds, New Zealand were surveyed 10 times. Additional information was gathered at 2 smaller colonies off D’Urville Island. The average total population was estimated to be 645 birds, with 92% at Duffers Reef, Trio Islands, Sentinel Rock, and White Rocks, including 102-126 breeding pairs, with an annual recruitment of 40-68 birds. Surveys before 1992 may have included only c. 40% of the population, because most counts seem to have been done during the middle of the day when significant numbers of shags were absent feeding. If historic counts at colonies are adjusted for birds absent feeding, numbers appear to have been stable for at least the past 50 years — and possibly over 100 years — which would suggest a long-term balance between recruitment and mortality.
Vegetation in the Esperance Valley, Milford catchment, Fiordland, as it was in February and March 1974, is described using quantitative data for part of the valley that included home ranges of two male kakapo (Strigops habroptilus). One home range, of only 1.8 ha, was sited at 700 – 730 m altitude and extended over a gently-sloping river terrace covered in snow totara (Podocarpus nivalis) scrub with short silver beech (Nothofagus menziesii) forest at its margins. The other home range was 4 ha in area, sited on a very steep (42°) valley wall mantled with unconsolidated avalanche debris at 800-860 m altitude, faced NW and was covered by Blechnum capense fern – shrubland and short silver beech forest communities. At that time, this valley differed from most other parts of Fiordland: although possums (Trichosurus vulpecula), stoats (Mustela erminea) and rats (Rattus spp.) were present, ungulates were absent or very localised. Results gave no indication that food was limiting kakapo numbers in the Esperance Valley and we conclude that, because of the extreme vulnerability of females and their eggs, nestlings and fledglings to introduced mammalian predators, stoats were the most probable primary cause of kakapo decline in Fiordland.
The timing and breeding success of starlings (Sturnus vulgaris) in nest boxes was monitored simultaneously at 5 localities representing northern, central, and southern New Zealand. The northern locality, (Kaikohe, 35° 25’S) was monitored for 2 consecutive years; the others, of which Winton (46° 10’S) was the southernmost, for 4 consecutive years. The median date for the laying of Oct clutches was always earlier at Winton except in 1978 when it was 4 Oct at both Kaikohe and Winton. In any 1 year the size of Oct clutches (4.43 pooled over all years and localities) and the number of young in successful broods was always greater at Winton than elsewhere. In both 1977 and 1978 the difference in laying dates between Ohau and Waikanae (only 27 km apart) was greater than between Kaikohe and Winton at opposite ends of the country. The 5 localities showed no consistent trend, one with another, in their respective median laying dates from 1 year to another. The mortality of chicks was highest at Kaikohe, except for Belmont in 1978 when the 65% mortality was attributed to stoats (Mustela erminea). The laying of 2nd clutches has a very weak genetic basis and is probably a response to environmental factors.
The Campbell Is snipe (Coenocorypha undescribed sp.) was unknown to science until its discovery on 19 ha Jacquemart I in 1997. Following the successful eradication of Norway rats (Rattus norvegicus) from 11,268 ha Campbell I in 2001, there was increasing evidence that snipe had begun to recolonise the main island: footprints were found at Monument Harbour in 2003, and a fully-feathered dependent chick was captured nearby in Mar 2005. A survey of Campbell Is snipe recolonising Campbell I was undertaken by the authors and a trained bird-locater dog during 7-15 Jan 2006. We confirmed the presence of snipe and their successful breeding at 2 sites: the outlet to Six Foot Lake (head of Monument Harbour), and near the mouth of Kirk Stream at the head of Six Foot Lake. We estimated at least 22 adult snipe to be present. Twelve adult snipe were caught, along with 5 dependent chicks with estimated ages ranging from 8 to 37 d. One snipe nest was found. Subsequent sightings in Feb 2006 revealed at least 2 snipe to be present on the north-western shores of Perseverance Harbour, c. 3 km north of where we recorded them. We document the successful re-establishment of snipe on Campbell I within 5 years of rat eradication, and recommend that their natural recolonisation be left to continue unaided.
Seasonal changes in home range size and habitat selection of kakapo (Strigops habroptilus) were investigated on Maud Island. Kakapo were radio-tracked at night in each of the four seasons between December 2000 and October 2001. Home ranges were estimated for four adult males, three juvenile males and two juvenile females in each season and for nine females in summer, each based on 20 radio-fixes per season. Home range size varied from 1.8 to 145.0 ha using the minimum convex polygon method. Home ranges were smallest in winter. Habitat selection was determined by overlaying the kakapo locations and home ranges on a vegetation map of the island. For each season selection ratios were calculated for each vegetation community. Pine plantation (Pinus radiata) was selected for in summer, whereas the treeland community dominated by five-finger (Pseudopanax arboreus) was selected for in the autumn. Dense pole stands of manuka (Leptospemum scoparium) and pasture communities were avoided by kakapo.
We studied the New Zealand morepork (Ninox novaeseelandiae) over 2 breeding seasons on Mokoia I, Lake Rotorua, North Island, New Zealand. Ten pairs were monitored in the 1995/96 breeding season and 8 in the 1996/97 season. Nest sites included tree cavities, hollows amongst tree fern fronds, nest boxes provided for saddleback (Philesturnus carunculatus) and scrapes on the ground. Nest cavities were 0-5.2 m agl. Clutch size was 1-3 eggs; egg dimensions averaged 39.0 mm × 32.9 mm. The incubation period for 1 clutch was at least 24 days. Only females were observed to incubate eggs and brood nestlings; males roosted nearby. Two chicks were weighed and measured throughout their development and the nestling period was determined for 1 chick. Nestling development is described. Breeding success was lower in the year after a poisoning operation to eradicate mice from the island. Juvenile mortality was high after fledging. The dispersal of 3 juveniles was monitored, and females appeared to move earlier and disperse farther than males.
The context of modern conservation management of kakapo is introduced and a brief overview of the research presented in this special issue of Notornis is provided.
182 bird taxa have been recorded from the Chatham Is archipelago, including 32 reported here that are additional to the most recently published reviews in 1990 and 1994. Nine of these new records are from subfossil bone deposits; the remaining 23 are new records of vagrants or colonists, although 2 result from taxonomic revision of albatross species, where it is not clear how many terminal taxa had been recorded before 1994. Antipodean albatross (Diomedea antipodensis), Salvin’s mollymawk (Thalassarche salvini), and Indian yellow-nosed mollymawk (T. carteri) were recorded breeding on the Chatham Is for the 1st time since 1994, with the latter being the 1st breeding record for the New Zealand region. Notable among the list of over 100 vagrant species recorded from the Chatham Is are the only New Zealand records to date of Atlantic yellow-nosed mollymawk (T. chlororhynchos), and willie wagtail (Rhipidura leucophrys).
The reproduction of kakapo (Strigops habroptilus) on offshore island refuges was monitored between 1990 and 2002. Productivity was primarily determined by the proportion of females that nested each breeding year. Within the same island, the proportion of females nesting each breeding year ranged between 33 – 95% but, as a proportion of the total female population, was just 5 – 42% between 1990 and 1999. The deliberate placement of the entire adult female population on Codfish Island (Whenua Hou) in anticipation of an exceptional fruit crop resulted in 95% of them nesting in 2002, raising 24 fledglings and increasing the total population by 39%. Although efforts to increase the frequency of kakapo breeding by providing supplementary food have been unsuccessful, nesting and fledging success increased significantly following the introduction of new, more intensive, management methods in 1995. Hatching success has, however, remained poor, with just 42% of eggs hatching. Comparison with related parrot species suggests that the kakapo’s hatching success is unusually low, perhaps because of inbreeding. Despite infrequent breeding and poor hatching success, the kakapo population has increased by 69% from 51 birds in 1995 to 86 in 2002. The female population has increased from 21 birds in 1995 to 41 in 2002, 20 of which are presently less than 10 years old.
Since the last review of kakapo biology, published 50 years ago, much has been learnt as a result of the transfer of all known individuals to offshore islands, and their intensive management to increase adult survival and productivity. This review summarises information on a diversity of topics, including taxonomy, plumage, moult, mass, anatomy, physiology, reasons for decline in distribution, present numbers and status, sex ratio, habitat, home range, foraging activities, diet, voice, breeding biology, nesting success, sexual maturity, and adult survival. In addition, those kakapo attributes that compromise its long-term survival in present-day New Zealand are discussed, along with management practises developed to overcome these problems.
Colony attendance and behaviour of non-breeding Buller’s albatrosses (Thalassarche bulleri) were studied at 2 Snares Is colonies in 2000-2004. Non-breeders comprised 31-32% of birds ashore in Mar-May (incubation to early chick-rearing), 44% in Jul (late chick-rearing), and 51% overall. Among non-breeders, the proportion of adults that had been recorded breeding in previous years decreased from 47% in Mar to 4% in Jul, with prebreeders (known-age birds that had not been observed breeding) dominating the composition overall (80%). The percentage of surviving birds seen ashore was 59% among prebreeders aged 6 years (modal age of first return), 88% among experienced prebreeders (birds that had been recorded ashore in >1 breeding season), 86% among remating (widowed or divorced) adults, and 63% among sabbatical (birds that had been recorded breeding in previous years, but were not breeding in the year of observation) adults. Colony attendance period was shortest among inexperienced prebreeders (latest birds to arrive), longest among 3rd year (i.e. known-age birds recorded ashore for the 3rd year) prebreeders (early arrival, late departure), and intermediate among last-time prebreeders and former breeders (early arrival, departure in mid-season). Failed breeders attended for up to 3 months, but departed after May irrespective of failure date. Birds stayed ashore for longer and at sea for shorter periods as they gained experience; the percentage of days ashore increased up to the 3rd prebreeding year, and was higher in males than females. Movements between colonies and subcolonies were most frequent during the first 3 prebreeding years. Prebreeders frequently joined display groups during their first 2 years (34% of observations in May), and associated with a nest site in May-Jul of their 3rd year. Among remating adults, displaying was most frequent in females and early in the season (Mar); their behaviour converged towards that of paired adults by May. Attendance patterns and behaviour were broadly similar to those of other albatrosses, except for earlier departure during the last prebreeding year not previously reported in an annually breeding species.
Sixteen of 26 hand-reared kakapo chicks (62%) have been successfully returned to the wild. These chicks were initially kept in thermostatically-controlled brooders, then in plastic tubs in an air-conditioned room, and finally a pen in an unheated room prior to transfer to an outdoor pen and release in the wild. Brooding temperature was progressively reduced to simulate the progressively longer period kakapo chicks spend in the nest without brooding. Humidity was maintained at 80% to simulate that measured in kakapo nests. Some chicks fed a relatively high fat diet within their first 20 days after hatching developed fatty liver disease; subsequently, chicks less than 45 days of age were fed a lower fat diet and older chicks gradually converted to a higher fat diet. Normal gut flora was successfully established in chicks by adding small quantities of adult kakapo faeces that had been screened for diseases and parasites. The growth rate of hand-reared chicks was significantly slower than that of parent-reared chicks during the first 40 days after hatching but there was no significant difference in growth rate in older chicks. Half the disparity in the growth rates of hand-reared and parent-reared chicks was due to the fact that most hand-reared chicks were suffering from ill health or injury before being taken into captivity. Two male chicks reared in isolation from other kakapo display varying degrees of sexual attraction to humans. The only sexually mature hand-reared female chick has mated and hatched a chick in the wild. Hand-reared kakapo comprised 40% of all chicks fledged since 1990 and presently comprise 20% of the total population of 86 birds.
Satellite telemetry was used between 1994 and 2004 to identify the distribution of 2 closely-related species of wandering albatross, Gibson’s (Diomedea gibsoni) and Antipodean (D. antipodensis), which breed in the New Zealand subantarctic. Trials of methods of attaching transmitters revealed that harnessed transmitters decreased foraging efficiency and increased mortality, whereas transmitters glued or taped on birds had little effect. There was some overlap in the species foraging ranges, but D. gibsoni mostly foraged in the Tasman Sea and D. antipodensis in the Pacific Ocean east of New Zealand. For both species the range of non-breeding birds was larger than that of breeders, but the core areas used by both breeders and non-breeders were similar. Non-breeding male D. antipodensis had the largest range, foraging off the coast of Chile, Antarctica and in the tropical South Pacific. In comparison, the range of D. gibsoni was small, with non-breeding male and female birds foraging westward to the south-eastern Indian Ocean but avoiding Antarctic waters. Individuals of both species and all stages of maturity had preferred but large foraging areas which lasted many years. Some seasonal trends in distribution were found. Both species preferred to forage at the outer edge of shelves and over seamounts, particularly where there were strong currents or eddies and productivity was enhanced, as well as over deep water. Over the past 40 years, longline fisheries used a minimum 89% and 53% of the range over which our study tracked D. gibsoni and D. antipodensis respectively. Of 18 D. gibsoni and 35 D. antipodensis banded birds recovered dead since 1971, 22% and 83% respectively were related to fisheries. The areas where closures of fisheries would be most likely to reduce bycatch are identified.
Photo essay compiled by Murray Williams from text an photographs provided by Don Merton, with additional photographs from Department of Conservation, Hocken Library and Archives New Zealand.
Breeding of North Island kokako (Callaeas cinerea wilsoni) was studied at Mapara, King Country, New Zealand, from 1990 until 2000. Sixty-seven adult and 167 nestling kokako were colour-banded, and radio-transmitters were attached to 49 to identify individuals and to help locate nests. Pair bonds were stable: 7% of pairs split each year for reasons other than mate death. More than 200 nests were located, which permitted observations of breeding-season length, nesting behaviour, clutch and brood size, incubation and nestling periods, and nest success. The nesting season began in late Oct but varied greatly in duration, lasting from 7 weeks in 1993/94 to 21 weeks in 1994/95. We attributed this variation to changes in abundance of key food fruits. Females made up to 5 breeding attempts and fledged as many as 6 chicks in a season. Male-male pairs also built nests, though the apportioning of effort differed from that of conventional pairs. Mean clutch and brood sizes were 2.31 and 1.96, respectively. The incubation period was 18 days and fledging took a further 34-42 days. Sixty-one percent of nesting attempts successfully fledged young when mammalian pests were controlled, as against 8% when there was no predator control. Predation of eggs and chicks by ship rats (Rattus rattus) and brush-tailed possums (Trichosurus vulpecula) was the main cause of nest failure, whereas deaths of nesting adult females mostly caused be stoats (Mustela erminea). Kokako are well adapted to cope with avian predation, but their future conservation depends on management of key small mammalian pests.