Ellenberg U.,Eudyptes EcoConsulting Ltd |
Ellenberg U.,University of Otago |
Ellenberg U.,La Trobe University |
Mattern T.,Eudyptes EcoConsulting Ltd |
And 4 more authors.
New Zealand Journal of Ecology | Year: 2015
Long-term population monitoring has become an important tool for conservation management and indicator of environmental change. In many species nest counts are used as an index of population numbers. A pilot study using double-counts in Fiordland crested penguins (Eudyptes pachyrhynchus) found that up to 12% of nests had failed following the first count, raising concerns about search-related disturbance effects and the reliability of long-term monitoring data. Here, we assess the impact of nest counts, and provide recommendations on how to reduce human disturbance effects during nest searches. In 2011, miniature temperature loggers (iButtons) were deployed into 120 nests to quantify temporary and permanent nest abandonment. Observations at nest sites allowed subsequent analysis of a range of factors potentially affecting penguin disturbance responses. In almost a third of all nests both first and second searches caused temporary nest abandonment that lasted up to 4.5 h, creating considerable predation opportunities. To reduce the likelihood of nest abandonment, counts are best conducted during the second half of the incubation period when nests are attended by single, wellestablished adults. Steep nesting areas proved suboptimal for long-term monitoring. Actual nest failure rates were low in 2011 (about 2% per search) and not all failures were immediately related to search disturbance. Hence, double-counts may be used in Fiordland crested penguins to improve nest count reliability as long as predation pressure is low and field protocols are adapted to minimise disturbance impact of nest searches. We show that well-designed research projects can inform and improve management decisions. For gathering reliable long-term population data, we encourage the reassessment of best-practice protocols to minimise monitoringrelated disturbance effects. © New Zealand Ecological Society.
Pryde M.A.,Science and Technical |
Pickerell G.,CMB 14056 |
Coats G.,PO Box 523 |
Hill G.S.,Te Anau Area Office |
And 2 more authors.
New Zealand Journal of Zoology | Year: 2013
Racumin® paste is an anticoagulant toxin increasingly being used for rodent control throughout New Zealand. Sachets containing Racumin® paste were distributed within the Eglinton Valley, Fiordland between July and November 2006 as part of a control operation targeting ship rats (Rattus rattus). Although the paste sachets were contained within bait stations, rats and possums were able to pull the sachets out of the stations exposing birds to the toxin. During a study of the breeding success of South Island robins (Petroica australis) within the Eglinton Valley, 50% of the robin pairs were known to be exposed to Racumin®. Direct consumption of baits or traces of Racumin® in several dead nestlings were noted. If bait sachets are unable to be secured, the use of this form of the toxin in areas where robins are present needs to be carefully considered or alternative toxins and matrices used. © 2013 Copyright The Royal Society of New Zealand.
Brownsey P.J.,Museum of New Zealand Te Papa Tongarewa |
Ewans R.,Te Anau Area Office |
Rance B.,Science and Technical Group |
Walls S.,Golden Bay Area Office |
And 2 more authors.
New Zealand Journal of Botany | Year: 2013
Sticherus tener is confirmed as being present on Resolution Island, Fiordland, extending from the northern half of Five Fingers Peninsula through to the centre of the island. It is also present on nearby Anchor Island in Dusky Sound, and on the Denniston and Stockton Plateaus. Sticherus urceolatus is newly recorded for New Zealand, with populations on the Stockton Plateau and near Takaka, and what appears to be a hybrid population on Indian Island, Dusky Sound. Plants of S. tener and S. urceolatus from northern South Island were previously identified as Sticherus flabellatus. Diagnostic characters for distinguishing the five species of Sticherus occurring in southern Australia and New Zealand, and a key to the New Zealand species, are provided. The distribution, ecology and conservation status of S. tener and S. urceolatus are outlined, and their biogeographic and evolutionary origins are discussed. © 2013 Copyright The Royal Society of New Zealand.
Grueber C.E.,University of Otago |
Maxwell J.M.,Te Anau Area Office |
Jamieson I.G.,University of Otago
New Zealand Journal of Ecology | Year: 2012
Translocation to island reserves is a common strategy in New Zealand and elsewhere for safeguarding species against introduced predators. When successful, however, the closed nature and relatively small size of many island sanctuaries can result in populations quickly reaching their carrying capacity, which in itself can present further challenges such as reduced productivity and population growth rates associated with densitydependent effects as well as increased rates of inbreeding. As part of its management strategy, small numbers of the highly endangered takahe (Porphyrio hochstetteri) were translocated during the 1980s and 90s from the last remaining natural population on the mainland of New Zealand to four offshore islands where introduced predators had been eradicated. We used logistic regression and generalised linear models to assess trends in population growth and recruitment and to evaluate whether the island metapopulation displays density-dependent effects on productivity. Our results indicate that the island metapopulation appears to have reached its carrying capacity, as reflected in an increasing ratio of non-breeding to breeding adults, and recent declines in juvenile production. These density-dependent effects are likely to constrain management strategies aimed at maintaining genetic diversity and minimising inbreeding. A recommendation to increase the immigration rate of takahe onto islands via translocations of birds from the source population on the mainland may be ineffective unless surplus birds are removed. © New Zealand Ecological Society.
Chilvers B.L.,Science and Capability Group |
Dobbins M.L.,Southern Islands Area Office |
Edmonds H.K.,Te Anau Area Office
New Zealand Journal of Zoology | Year: 2015
Yellow-eyed penguins (hoiho, Megadyptes antipodes) are a Nationally Vulnerable species, restricted in distribution to the lower South Island, Stewart Island/Rakiura, and the New Zealand sub-Antarctic islands. The foraging behaviour of penguins is considered an indicator of marine ecosystems because when breeding they rely on the availability of prey close to their nests. Time-depth recorders were attached to eight nesting hoiho at Port Pegasus/Pikihatiti, Stewart Island. While at sea, hoiho spent 55% of their time diving in water > 3 m deep. Their mean dive depth was 61 ± 6.1 m with mean dive duration 2 ± 0.1 min. Based on bathymetric charts, hoiho could undertake these dives < 10 km from their nesting sites. There was significant variability in hoiho foraging behaviour within New Zealand depending on bathymetry and anthropogenic impacts. Understanding hoiho foraging behaviours could help to determine to what extent they impact on this species' life history and its role as an ecosystem indicator. © 2014 © 2014 The Royal Society of New Zealand.