Brown teal (Anas chlorotis) populations at Clendon Cove and Tutaematai in Northland, New Zealand, declined catastrophically between 1993 and 1995, from 31 pairs to 1 and from 22 pairs to 8, respectively. Mean productivity was 1.8 fledglings pair1 in both populations. Fledgling survival was almost nil with only 1 of 51 identifiable fledglings surviving to recruit into 1 population. Almost all fledgling mortality occurred within 3 months of independence. Annual adult survival was 15% at Clendon Cove and 43% at Tutaematai and most deaths occurred in October-December, immediately after breeding. At Clendon Cove, significant mortality also occurred in autumn. Destruction of breeding and refuge habitat by cattle seeking moisture during periods of drought was identified as a significant cause of decline.
Bird records from the Snares Islands between Dec 1982 and Oct 2000 are summarised. Population estimates and distributions are given for the 29 breeding species. Bird species recorded breeding on the Snares Is for the first time since 1982 were southern black-browed albatross (Diomedea melanophrys), Chatham Island albatross (D. eremita), mallard (Anas platyrhynchos), southern black-backed gull (Larus dominicanus), fantail (Rhipidura fuliginosa), and starling (Sturnus vulgaris). Fantails are now abundant on the Snares Is. Published work on the breeding chronology and breeding success of 8 intensively studied species is summarised, and new information on breeding ecology is presented for all breeding species. Sighting of 70 non-breeding and vagrant species are summarised; 34 of these were new records from the Snares Is since 1980. The total bird list for the Snares Is is now 99 species, with a further 8 species reported from boats offshore.
The population of white herons (Egretta alba) at Waitangiroto Nature Reserve has been monitored since 1944. The number of breeding adults (estimated from maximum number of nests at the height of the breeding season, and first recorded in 1958) has increased from 26 to c.100, with a concurrent increase in the number of chicks hatched and fledged. Population growth was greatest between 1964-69 and 1980-84. Chick mortality appears to result largely from the effects of westerly and southwesterly storms in October and November, although infanticide, siblicide, and low levels of predation may account for some chick deaths. The mean number of fledglings nest-1 has decreased over time as the number of nests has increased, suggesting a density dependent response. The white herons that “invaded” New Zealand from Australia in 1952 and 1957 did not appear to recruit into the breeding population.
The benefits of monitoring habitat use patterns of translocated populations are widely acknowledged. However, this monitoring seldom occurs. Here, I report the habitat use and foraging patterns of a newly translocated population of South Island saddlebacks (Philesturnus carunculatus carunculatus) on Motuara Island, New Zealand, during the 1st breeding season after release. Reintroduced South Island saddlebacks spent most foraging time on the ground and in Pseudopanax arboreus. Foraging substrates used by male and female saddlebacks differed significantly Saddlebacks focused foraging activities at 0-4 m above ground, and appeared to prefer to forage in larger trees, although the species composition of forested areas did not seem to influence the birds’ choices of places to settle. With increasing population density, saddlebacks on Motuara Island may increase their areal foraging eficiency by using a wider range of plant species, vertically stratifying foraging locations within pairs, increasing use of smaller trees for foraging, and possibly by using scrub habitats more extensively South Island saddlebacks appear to be highly adaptable in their choice of foraging sites and this plasticity may enhance the success of translocations.
The Chatham Island pigeon or parea (Hemiphaga chathamensis) is an endangered species of pigeon endemic to the Chatham Islands. Effective conservation management of the Chatham Island pigeon required an understanding of its ecology and identification of the causes of decline. We studied the pigeon in their last remaining stronghold; the south-west of Chatham Island, New Zealand, between July 1991 and December 1994. We describe the nesting behaviour, nesting success, and the dispersal, survival, and recruitment of juveniles. The study was confounded by the lack of information on predator numbers or outcomes of pigeon nests from before the start of predator control activities within and adjacent to our study area. Despite a previously reported decline in pigeon numbers up until the early 1990s, during this study there was a 3-fold population increase, and only a low level of predation by possums and rats. Other than predation, no factor which might previously have limited the pigeon population was identified. We assume that the trapping and poisoning of pest-mammals since 1989, has been sufficient to allow the population of Chatham Island pigeon to recover.
Numbers of brown teal (Anas chlorotis) present at summer flock sites in Northland, New Zealand declined 65% during 1988-99 and the species’ principal range contracted to three enclaves located along 20 km of the eastern coast. Most populations underwent a period of gradual decline followed by an abrupt crash, symptomatic of prolonged recruitment failure. Drought-induced habitat and landscape change is proposed as an important agent of decline in two formerly large populations at Clendon Cove and Tutaematai. Extirpation in Northland appears imminent.