Many bird species have been successfully introduced beyond their natural range, some becoming more abundant in their new environment than in their country of origin. In this study, bird density was measured at 2 study areas comprising a total of 48 recreational parks in northern England and Canterbury, New Zealand, for 10 focal species (native to the former, introduced to the latter). Site characteristics and presence of other bird species were also recorded and investigated as potential explanatory factors for differences in density between the 2 study areas. Common redpoll, common starling, European greenfinch and house sparrow had significantly higher densities at the New Zealand sites. Analysis using generalised linear models revealed a negative relationship between common starling density and proportion cover of trees and shrubs, and a positive relationship between common redpoll, common starling and European greenfinch densities and site species richness. However, since there were no significant differences in site characteristics or site species richness between study areas, these relationships could not account for higher densities at the New Zealand sites. There was an apparent negative relationship between densities of common starling and house sparrow and foraging guild diversity, suggesting that interspecific competition may contribute to differences in density between study areas. The proportion of variation explained by the models was relatively low, suggesting that there may have been missing variables that influenced species density. More detailed study of a wider range of variables is required to investigate this further.
The remnant wild populations of the critically endangered orange-fronted kākāriki (Cyanoramphus malherbi) are restricted to 3 North Canterbury valleys where they co-occur with the yellow-crowned kākāriki (C. auriceps). Mixed pairs of Cyanoramphus kākāriki species have been documented throughout the genus, but the extent to which orange-fronted and yellow-crowned kākāriki mate assortatively, particularly when one species outnumbers the other, remains unclear. Here, we investigate the level of assortative mating between orange-fronted and yellow-crowned kākāriki. Based on 355 confirmed nests during 1999-2011, 99% (n = 351) were pure pairings and 1% (n = 4) were mixed pairings. With one exception, the ratio of orange-fronted to yellow-crowned kākāriki encountered during annual surveys ranged between zero and 0.78. These results indicate that the 2 congeners exhibit assortative mating, even when the orange-fronted kākāriki is outnumbered by yellow-crowned kākāriki. The low levels of mixed pairing we observed suggests that the reintroduction of orange-fronted kākāriki should not be precluded to sites where yellow-crowned kākāriki already occur.
Monitoring of wetland birds was undertaken at Lake Ellesmere/Te Waihora during the post-breeding period in February 2006, 2007 & 2008. Census totals were 38,726, 39,917 and 39,175 individual birds over the 3 years, respectively, and 46 wetland bird species were recorded. Nine species had a maximum count exceeding 1000 individuals, including 11,245 grey teal (Anas gracilis), 10,651 black swan (Cygnus atratus), 5776 pied stilt (Himantopus himantopus), 4899 Canada goose (Branta canadensis), 3405 Australasian shoveler (Anas rhynchotis), 1873 banded dotterel (Charadrius bicinctus), 1640 paradise shelduck (Tadorna variegata), 1592 black-billed gull (Larus bulleri) and 1389 mallard/grey duck (A. platyrhynchus/A. superciliosa). Fourteen species were recorded in numbers that met or exceeded the 1% Ramsar international significance criterion: Australasian crested grebe (Podiceps cristatus), black cormorant (Phalacrocorax carbo), white heron (Ardea modesta), black swan, paradise shelduck, grey teal, Australasian shoveler, pied stilt, black stilt (Himantopus novaezelandiae), banded dotterel, wrybill (Anarhynchus frontalis), black-billed gull, black-fronted tern (Childonias albostriatus), and Caspian tern (Hydroprogne caspia). Lake Ellesmere also supported populations of migratory bird species that are uncommon in New Zealand including curlew sandpiper (Calidris ferruginea), sharp-tailed sandpiper (C. acuminata), red-necked stint (C. rufficolis), Pacific golden plover (Pluvailis fulva) and white-winged black tern (Childonias leucopterus). When compared to other coastal wetlands in terms of bird numbers, Lake Ellesmere ranked as the most important site in the Canterbury Region.
We used data from 3 sources to examine the population size and trend of Salvin’s albatrosses (Thalassarche salvini) breeding on Proclamation Island, Bounty Islands, New Zealand. Island-wide counts of breeding birds during incubation resulted in totals that declined 14%, from 3065 in 1997 to 2634 in 2004. A count of breeding albatrosses over part of the island in 2011 indicated a further decline of 13% between 2004 and 2011, and an overall decline of 30% between 1997 and 2011. Additional counts on part of Depot Island indicated a decline of 10% in the numbers of breeding pairs between 2004 and 2011. Daily observations of 70 nests showed that hatching spanned the period from 5 to 21 November 1997, with a median of 15 November, apart from 5 eggs that had not yet hatched by the end of the study period. Based on the banding and recapture of chicks banded in March 1985 annual survival was estimated at 0.926. The scale of the decline estimated in this population has resulted in the conservation status of Salvin’s albatross being upgraded from nationally vulnerable to nationally critical.
Discriminant function analysis (DFA) was used to determine gender and geographic variation in the morphometrics of white-chinned petrels (Procellaria aequinoctialis) measured from fisheries bycatch in New Zealand. Samples were divided into 5 clusters based on capture location. A DFA model was created using adult breeding birds presumed to be from the 2 main locations at the Auckland Islands and Antipodes Islands. Geographic variation in head and bill, skull width, culmen, culmen depth at base, culmen width at base, right and left mid-toe and claw, tail, and right and left wing was found between birds presumed to be from the ‘Auckland’ and ‘Antipodes’ clusters, with ‘Antipodes’ birds being generally larger than ‘Auckland’ birds. Gender variation in head and bill, skull width, culmen, culmen depth at base, culmen width at base, minimum bill depth, right and left mid-toe and claw, right wing, right and left tarsus existed for ‘Auckland’ birds. Gender variation in head and bill, skull width, culmen, culmen depth at base, culmen width at base, minimum bill depth, right and left mid-toe and claw, and tail existed for ‘Antipodes’ birds. Birds in the other 3 clusters were classified as originating from the Auckland Islands or Antipodes Islands. The clustering suggested that birds from the Auckland Islands tended to forage mostly north and west, whereas birds from the Antipodes Islands foraged mostly towards the north. There were large overlaps at Puysegur Point and particularly the Chatham Rise of birds from both breeding locations. This study shows the usefulness of bycatch necropsies, and emphasises the need for further studies in geographic variation and sexual dimorphism at all New Zealand breeding locations.
The Chatham Island duck (Anseriformes: Anatidae: Anas chathamica) had a pronounced and rugose enlargement to the tip of the processus extensorius at the proximal end of its carpometacarpus. This “carpal knob” was the equal in size of those found in some much larger waterfowl (e.g., steamer ducks, Tachyeres sp.), and was disproportionately larger than those of all other New Zealand waterfowl. The knobs on 20 carpometacarpi examined all showed evidence of continuous bone deposition at their tips and their use as weapons is implied. Comparisons with other duck species having similarly prominent and rugose carpal knobs suggests the Chatham Island duck maintained long-term pair bonds and occupied combined feeding and breeding territories year-round which both sexes defended belligerently.
Banded rails (Gallirallus philippensis) were surveyed in saltmarshes and mangrove fringed habitats at Onerahi, Whangarei, New Zealand. A total of 13 sites were surveyed 3 times per year around sunset during late spring in 2004, 2007 and 2013. On average 4.41 calls were heard per hour. Banded rails were detected at 12 sites with between 0.01 and over 2 ha of saltmarsh and extensive mangroves, but not a saltmarsh site lacking mangroves. Occupancy models favoured those with no change in occupancy state, seasonal detection, and there was with some support for random colonisation of sites. Records from Awaroa Creek indicate that rails can be detected from late afternoon calls throughout the year. Surveys should include the half hour before until at least 10 minutes after sunset.
Discriminant function analysis (DFA) is widely used to determine sex in the field from morphological measurements of bird species with monomorphic plumage. Sexual dimorphism was examined in black petrels (Procellaria parkinsoni) using 7 external measurements of adult birds breeding on Great Barrier Island, New Zealand. Males were significantly larger than females in absolute values of all measurements except for tarsus. Two stepwise DFA models were developed. The first used all 7 parameters, while the second model used only 6 parameters in order to increase sample size. Model one and two showed an 88 and 82% classification success, respectively, most likely due to the high overlap in measurements between males and females. These canonical functions were not accurate enough for field surveys, but may be improved using a larger and more representative sample size.
Flesh-footed shearwaters (Puffinus carneipes) are considered to be one of New Zealand’s seabird species that is most heavily impacted by both commercial and recreational fisheries, yet they have an IUCN ranking of “Least Concern”. To resolve this contradiction we conducted surveys on 3 large breeding colonies and compared our results to historical data. We found that the burrow density on the most northerly island (Lady Alice Island/Mauimua) has increased since the last set of surveys; however the density of flesh-footed shearwaters nests has remained stable. At the largest colony we surveyed (Ohinau Island), the density of burrows has remained stable, while the density of nests has declined. At New Zealand’s most southerly colony (Titi Island), both burrow and nest densities have remained stable. Our results suggest that the status of flesh-footed shearwaters populations in New Zealand is variable with 2 populations that are stable and 1 that is declining. Nevertheless, due to the short time period between our surveys and the historical data, repeated surveys in the future are needed to determine if further declines in the largest colony warrant a reassessment of the status of this species.
Of 4 importations of Canada goose Branta canadensis into New Zealand, 2 (in 1905, 1920) resulted in breeding. Commencing in 1907, multiple and repeated releases of the 1905 geese and their progeny had, by 1922, established flocks of several hundred distributed along the eastern Canterbury and Otago foothills of the Southern Alps. Thereafter, the geese spread widely but remained resident and breeding only in the South Island. Establishment of Canada geese in North Island commenced in 1969 with the first of 4 transfers by the Wildlife Service, collectively totalling 280 birds from Canterbury’s Lakes Ellesmere and Forsyth, to coastal Wairoa lakes and nearby locations. The Wildlife Service assisted numerous other transfer and release initiatives, of at least 800 birds, in North Island in the 1970s and 1980s, principally by Wellington and Auckland Acclimatisation Societies, Ducks Unlimited, and private waterfowl enthusiasts. At the same time it supported transfers of 450 geese to the South Island’s West Coast. From these multiple releases Canada geese have become widespread in rural New Zealand.
Kiwi (Apteryx spp.) are the most vocal of the ratites. Of the 5 Apteryx species only 2 have previously been subject to detailed vocal analysis: the North Island brown kiwi (A. mantelli) and the little spotted kiwi (A. owenii). This paper describes the vocalisations of the great spotted kiwi (A. haastii), the largest of the Apteryx species. Acoustic recorders were installed near the breeding den sites of 7 great spotted kiwi pairs residing in Hawdon Valley, Canterbury between November 2012 and March 2013. A total of 133 whistle vocalisations from 10 individuals were subject to detailed temporal and spectral analysis. Male and female syllables were found to be sexually dimorphic; syllables in male calls tended to be longer and more highly pitched than their female counterparts. Despite this dimorphism, patterns of intra-call variation were consistent between the sexes. It appears that intra-call variation is a trait which varies markedly within the Apteryx genus.
Prior to 1992 the total population of New Zealand king shag (Leucocarbo carunculatus) was estimated to be about 300 individuals. Between 1992 and 2002, colonies in the outer Marlborough Sounds, New Zealand were surveyed by boat and the total population was estimated to be 645 birds. About 92% of all birds occurred at Duffers Reef, North Trio Island, Sentinel Rock, and White Rocks, with an estimated 102-126 breeding pairs. A survey in February 2015 was the first to be conducted from the air. All colonies were photographed within 44 minutes prior to the morning departure and the total population was estimated to be 839 individuals. A total of 187 pairs/nests were recorded using aerial 3D images of all breeding colonies in June 2015. North Trio Island was the largest breeding colony with 33.7% of all nests, followed by Duffers Reef with 18.7% of all nests. Despite the larger revised population size, the species remains Nationally Endangered.
The white-flippered penguin (Eudyptula minor albosignata) population on Banks Peninsula, New Zealand, was extensively preyed on by mammalian predators during the 1980s and 1990s with the loss of many colonies and the reduction in size of others. This paper presents the results of a 20-year study designed to identify the predators primarily responsible for these losses. It was based on the monitoring of 9 colonies ranging in size from 2 to 37 nests on a 1.7 km section of rocky coastline. Predators were trapped in the largest colony to determine the species present and their relevant behaviour. The other colonies were left unprotected, 6 of which were accessible to predators and 2 were not. Predation of penguins was first observed in the area in 1981 and it occurred annually through to the end of the study in 1995. Five of the 6 unprotected colonies were lost in 1982 and 1983 while the inaccessible colonies were unaffected. The remains of penguins that had been preyed on were found in the ‘protected’ colony in 11 of the 15 years between 1981 and 1995. These had been taken during the second half of the moulting season in February, and during the non-breeding season from April to August. No predation was observed during September to January when the penguins were breeding. A total of 47 mustelids were trapped in the ‘protected’ colony of which 43 (91%) were ferrets (Mustela furo). Overall there were 16 instances of predation that could be attributed to ferrets and 1 that was attributed to a ferret although the predator was not caught. The onset and sustained period of penguin predation by ferrets followed an eruption in their numbers Banks Peninsula-wide. This was most likely triggered by a corresponding increase in the numbers of rabbits (Oryctolagus c. cuniculus), their primary prey.