Control of a stoat (<i>Mustela erminea</i>) population irruption to enhance mohua (yellowhead) (<i>Mohoua ochrocephala</i>) breeding success in New Zealand

The mohua (or yellowhead, Mohoua ochrocephala) is an endangered hole-nesting passerine which is now absent from >75% of its former range. This paper describes an 11 year monitoring programme, which was set up to survey 14 populations at 12 key sites throughout the range of the mohua, in order to document the pattern of population change and provide early warning of likely local extinctions. Between 1983 and 1993, one mohua population became extinct. Five of the 14 populations declined significantly, and three of these were on the verge of extinction by 1993. One population increased, and seven did not change significantly, although a declining trend was recorded at five of these. Six population crashes coincided with irruptions of stoats (Mustela erminea) following heavy beech (Nothofagus) seeding.

Section: Results Of the Monitoring Programmementioning

confidence: 99%

Section: Catlins Forest South Otago (Nzms 260 G46)mentioning

confidence: 99%

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Monitoring mohua (yellowhead) populations in the South Island, New Zealand, 1983–93

O’Donnell¹

1996

“…Native fauna in New Zealand forests are at risk from predation by introduced mammals, especially the ship rat (Rattus rattus), and the stoat (Mustela erminea) (Innes & Hay 1991;King et al 1996;O'Donnell et al 1996). Large-scale poisoning by aerial application or bait stations is used routinely to control rats and another pest species, the Australian brushtail possum (Trichosurus vulpecula) New Zealand Journal of Zoology, 1998, Vol.…”

Section: Introductionmentioning

confidence: 99%

Effects of rat‐poisoning operations on abundance and diet of mustelids in New Zealand podocarp forests

Murphy¹,

Clapperton²,

Bradfield³

et al. 1998

This study aimed to quantify the changes in numbers and diet of stoats, weasels and ferrets following rat and possum poison operations in two podocarp-hardwood forests between 1989 and 1995. Poison operations were classified according to their success in reducing rat numbers, and if they used an acute toxin (1080) or an anticoagulant (brodifacoum or pindone). Stoat catch rates followed the same seasonal patterns as rat footprint tracking rates, and stoat catch rates were positively correlated with rat catch rates. Rat numbers in spring had no significant relationship with the number of juvenile stoats caught in summer. Stoat catch rates did not vary significantly with poison-operation type over a six month period, but all three successful anticoagulant operations resulted in lower stoat catch rates than did Z98003 Received 9 January 1998; accepted 22 June 1998 unsuccessful operations. Brodifacoum in bait stations may have lowered stoat numbers by secondary poisoning for the first 2-3 months, but thereafter there was no apparent effect. The sex ratio of stoats caught varied significantly amongst the poison operations. The fewest females were caught following anticoagulant operations. Stoat stomachs and intestines contained mostly rats, and some birds and mice. Weasels ate mostly mice, while ferrets predominantly ate lagomorphs and invertebrates. Male and female stoats ate similar proportions of rats, but females ate more mice. Both sexes, but particularly females, ate fewer birds in autumn and winter than in spring and summer. Stoats shifted between eating rats and birds, depending upon the abundance of rats. Thus successful rat-poisoning operations resulted in higher bird consumption than unsuccessful ones. Combining the numerical and functional responses of stoats into a 'bird predation index' showed that stoats are likely to have the greatest effect on birds after successful 1080 poison operations. Diet shifts could not be demonstrated in weasels or ferrets because sample sizes were too small for quantitative assessments. The risk of increased predation pressure on birds from diet-shifting by stoats must be balanced against the predation pressure on birds and other ecological impacts of rats and possums from different poison operations.

“…During the summers of 1987/88 and 1990/91, there were stoat irruptions in Eglinton Valley, and consequent high rates of predation of mohua nests (Elliott 1990;O'Donnell et al 1996). During these years, successful nests were higher above the ground than failed ones (Table 1; P = 0.016), and more often in red beech than silver beech (x 2 = 4.571, d.f.…”

Section: Comparison Of Successful and Unsuccessful Nest Sitesmentioning

confidence: 99%

Nest site selection by mohua and yellow‐crowned parakeets in beech forest in Fiordland, New Zealand

Elliott

Dilks²,

O’Donnell³

1996

Self Cite

Nest site selection in two hole-nesting forest birds, mohua (yellowhead, Mohoua ochroeephala) and yellow-crowned parakeet (Cyanoramphus auriceps), was investigated. Parakeets nested in a w ide range of cavities ranging in size up to half a metre across. In contrast, mohua used small cavities that support the sides of their cupshaped nests. Most parakeet nests were found in red beech trees (Nothofagus fusca), which have many large cavities, and both species nested most often in trees >70 cm in diameter. Nest sites arc very numerous in our study area and are probably not limiting for either species in similar forests throughout Fiordland. However, neither species is likely to be able to nest in beech forests managed for timber production, in which most trees will be large enough for nesting only just before they are harvested. Although long-tailed cuckoos (Euclynamvs taitensis) parasitise mohua nests and prey upon their nestlings, most mohua nest holes arc too small for cuckoos to lay eggs in. High nests of both species are less likely to be preyed upon by stoats than low ones. Neither species shows adaptive preferences for small nest holes or high nest sites. This paper presents a novel way to analyse the use of nesting cavities using capturerecapture analysis.