Singing and territorial behaviour of North Island tomtits (Petroica macrocephala toitoi) were used to monitor population size over a 3-year period at Atuanui, Mount Auckland Scenic Reserve, North Auckland. Male tomtits were observed singing year-round with singing peaking in the period from Nov to Jan. The general territorial behaviour of Atuanui tomtits was similar to that reported for other North Island populations, with territorial males resident in all months and most territories occupied in successive years. Density of territories was stable over the 3-year period but vacancies in suitable habitat suggest the population is not at carrying capacity.
During 1971-75 and 1991-95, surveys of Caspian tern (Sterna caspia) colonies throughout New Zealand were carried out. The breeding population in 1971-75 was 1266 pairs, in 16 colonies, predominately in the northern North Is. In 1991-95, there were 1190 breeding pairs found in 17 mainly northern colonies, suggesting the population had been relatively stable over the 20-year period. As census methodology may under-record the breeding of isolated pairs, we included an estimate of the number of isolated pairs to give a total national population of 1300-1400 breeding pairs. This is less than 3% of the global population. Colony size and location showed some change between survey periods; 6 colonies disappeared and 8 new colonies were formed. Addition surveys in 2011-2015 are recommended to compare recent population trends.
I conducted road counts on the North I and South I of New Zealand in Mar 2006 to evaluate relative abundance and distribution of Australasian harriers (Circus approximans). Over 1670 km were traveled on the North I with 98 harriers detected, yielding 1 harrier/17.0 km traveled. Over 2430 km were traveled on the South I with 145 harriers detected, yielding 1 harrier/16.8 km traveled, with no difference in number of harriers detected/km traveled between islands (P > 0.25). Three survey routes, 1 on southeastern North I and 2 on northeastern and east-central South I, were particularly productive yielding 1 harrier/7.1-11.1 km traveled. My results provide empirical support for the frequently cited description that the Australasian harrier is now New Zealand’s most abundant native diurnal raptor, and has largely benefited from the conversion of land from native forest and scrub to pasture at the likely expense of other native and endemic species.
The effects of a range of habitat variables on spatial variation of breeding burrow density of sooty shearwaters, Puffinus griseus, were measured on 5 islands near Rakiura (Stewart Is) and 1 island in The Snares Is group, during the 2000-01 breeding season. Density estimates for 4 islands where Rakiura Maori harvest chicks ranged from 0.30 to 0.47 burrows per m2. Density on 2 non-harvested islands occurred at opposite ends of the burrow density spectrum (Whenua Hou, 0.09 entrances per m2; The Snares, 0.90 per m2). Burrow density was consistently lower in areas with shallow soil, in inland areas, and where there was more plant debris on the forest floor. The latter may reflect cause or effect because the birds drag woody and leafy debris into their burrows to form nests and to block the burrow entrance. Large amounts of variation in burrow density were not explained by habitat predictors. Detection of harvest impacts on sooty shearwater density on harvested and non-harvested islands will be more powerful if models account for soil depth and island edge-effects, but disregard vegetation variation.
In Jul and Aug 2005, 18 North Is kokako (Callaeas cinerea wilsoni) were released into a 450-ha area of New Zealand native forest subject to intensive control of introduced mammalian predators. The area, Ngapukeriki (near Omaio, Bay of Plenty, New Zealand), lies within a 13,000-ha matrix of native and exotic forest subject to lower and variable degrees of predator control. In contrast to most previous kokako translocations, this project employed 3 tactics to maximise the likelihood that kokako would remain in the target area: 1) many birds were released in a short period; 2) playback of kokako song was broadcast in the release area (potentially creating an “acoustic anchor”); and 3) a kokako pair was held at the release site in an aviary. Most birds approached to within 20 m of playback speakers, some approaching repeatedly. Several interactions between released birds were observed, including vocal interactions and instances of birds associating with one another temporarily. Visits to the aviary pair were rare. On 13 Apr 2006, all 8 trackable birds and 4 birds whose transmitters had failed remained in the core management area; locations of remaining birds (with lost or non-functional transmitters) were unknown. At least 5 territorial pairs had formed, and 1 chick was known to have fledged. To our knowledge, this was the 1st time song playback had been used as an attractant in a terrestrial bird reintroduction.
Natal dispersal of the New Zealand falcon (Falco novaeseelandiae) was documented using relocations of radio-tagged and colour banded falcons in Kaingaroa pine plantation. The age at which fledglings commenced natal dispersal was highly variable. The earliest fledglings dispersed 42 days after fledging, whilst others did not disperse out of their natal territories, remaining there to breed. After 91 days, 87% of fledglings had begun dispersal out of their natal territory. The mean time for the onset of dispersal was 76 days. Males generally dispersed earlier than females, but no significant difference was recorded. Both radio telemetry and colour band recoveries indicated that a large proportion of fledglings dispersed out of the study area. Mean natal dispersal distance within Kaingaroa Forest was 9.6 km. No significant difference was observed in natal dispersal distances between the sexes, although males generally roamed further afield than females. During this study, several females were recorded successfully breeding during their 1st year, a year earlier than usual. Males did not attempt to breed until they were 2 years old. We conclude that the high emigration rates and favourable breeding conditions in pine plantations make these habitats highly likely to act as source populations for neighbouring areas where populations of the New Zealand falcon may be in decline.
A stable evidence-based taxonomy is a critical requirement for the effective future conservation of the albatrosses. Recently published partial molecular phylogenies are in broad agreement with respect to the structure of the evolutionary tree for most named taxa, but the analytical methods used to create them have been seriously criticised and they must be considered provisional at best. A further problem is that their authors reach startlingly different conclusions regarding the numbers of taxa which should be recognised as species; 13 vs. 24. Here, we attempt to resolve this situation by supplying full length mitochondrial cytochrome b data presently missing for 2 taxa, carrying out thorough phylogenetic analyses meeting the requirements of published prescriptions and taking into full account other sources of new molecular data and contemporary opinions on albatross nomenclature and the status of taxa. We provide general support for the published trees and critically evaluate claims regarding how many taxa represent full species. Some genetic distances between pairs of taxa are so small that considerable weight of alternative evidence is required to support any decision leading to a recommendation to split them. We note that the empirical boundary between consensus and controversy falls at or around 1% DNA sequence divergence and further that few, if any, commentators recognise taxa that are separated by less than 0.1% as being valid species.
The kaka (Nestor meridionalis) is an endemic parrot of New Zealand, and is nationally endangered. Conservation of the species is primarily dependent on intensive control of introduced mammalian nest predators, particularly stoats (Mustela erminea) and brushtail possums (Trichosurus vulpecula). Breeding was studied in 4 sites: Waipapa (1996-2002) and Whirinaki (1998-2002) in the North Island, and Rotoiti (1997-2002) and Eglinton (1998-2002) in the South Island. In total, 145 nests were found. The proportion of radio-tagged females that bred at a site in a given year varied from 0-100%, with most breeding occurring in years of mast-fruiting or seeding by key food tree species. Kaka nested mainly in trunk cavities of live canopy or emergent trees. Egg-laying occurred from Oct to Mar, but differed between years within sites by up to a month, and was usually 2 months later at the most southern site (Eglinton) than elsewhere. Mean egg length was 41.5 mm, mean maximum breadth was 31.5 mm, and fresh egg mass was 22.6 g or 5.65% of female body weight. Clutches consisted of 1-8 eggs, most being of 3, 4 or 5 eggs (mode = 5), and mean clutch size did not differ significantly between the sites. The female alone carried out incubation, with her mate feeding her 8-12 times a day. Overall, hatching success varied from 39-66% between sites, but it also varied between breeding seasons at each site, in part due to the level of control of introduced predatory mammals. Kaka nestlings were covered in white down at hatching, and left the nest when c. 70 days old. Even when 11-20 days old, they were left unattended at night for 20-70% of time and by day for 50-85% of time. Twice females were filmed aggressively attempting to evict stoats that had killed broods in their nest cavities. Breeding productivity (proportion of eggs that produced fledglings) in the 4 study sites varied from 19% at Whirinaki (no control of predatory mammals) to 53% at Eglinton (intense control of predatory mammals). The implications of the breeding biology of the kaka are discussed in relation to conservation management of the species.
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.
Stewart Island/Rakiura, the third largest island in New Zealand, has not had the large-scale forest clearance and introduction of mustelids that has had deleterious impacts on populations of native forest birds on the North and South Islands. However, Stewart Island has had 3 rat species, feral cats and possums introduced, which are known bird predators. It is likely that these species have had serious consequences for the native birds there. As no review of forest birds had been done within the past 80 years, an evaluation of changes in the reported abundance of native bird species on Stewart Island over the past 100 years was carried out, which revealed relatively recent declines and extinctions. Brown teal, rifleman, mohua, South Island kokako, falcon, Stewart Island weka and probably yellow-crown parakeets, have gone extinct on Stewart Island within the past 50 years. Birds showing dramatic declines in the past 100 years include kereru, kaka, kakapo, and robin. Populations of native birds on Stewart Island showed similar patterns of extinctions and declines as the South Island despite fewer agents of decline.