Source Author Year Title Quote
NZ J Ecology 38: 103-109 C.J. Veltman et al. 2014 A principles-based decision tree for future investigations of native New Zealand birds during aerial 1080 operations “Although the presence and protection of remnant mohua populations is often one of the drivers for aerial distribution of 1080 baits in South Island beech forests…the fate of individual mohua following such operations remains unknown.”
Otago Daily Times Online News 7/12/13 Rebecca Fox 2013 Beech 1080 blitz possible: Doc “Doc scientist Dr Graeme Elliot said a large mast and resulting rat plague in 2000 caught Doc by surprise and there were huge losses of birds, including the loss of a mohua population at Mt Stokes in the Marlborough Sounds and a population in the Eglinton valley in Fiordland, which was reduced from several hundred to a dozen or so birds”
Otago Daily Times Online News 7/12/13 Rebecca Fox 2013 Beech 1080 blitz possible: Doc “The Mohua Charitable Trust had been doing trapping work in the Makarora Valley and it would be the first time Doc had considered a 1080 programme there”
NZ J Ecology 36: 131-140 C. O’Donnell & J. Hoare 2012 Quantifying the benefits of long-term integrated pest control for forest birds populations in a New Zealand temperate rainforest “An inventory of the forest bird population of the Landsborough Valley was conducted in 1985…The inventory noted significant bird populations in the valley, including the largest population of mohua…in the region…The site was recommended for protection…At the time, research indicated that predation by stoats (Mustela erminea) was a major cause of decline in mohua populations throughout the South Island, and that, for populations to be maintained or recover, predator control at those sites would be required.”
NZ J Ecology 29: 69-82 D. Kelly et al. 2005 Can stoat (Mustela erminea) trapping increase bellbird (Anthornis melanura) populations and benefit misteltoe (Peraxilla tetrapetala) pollination? “Several studies on other forest birds have found that trapping can reduce the high predation pressure during stoat irruptions. O’Donnell et al. (1996) found that a very intensive trapping programme significantly reduced stoat predation on breeding mohua during a stoat irruption.”
Rarebits 52 DoC 2004 newsletter The stoat control line in the Landsborough Valley has recently been extended down to Harper Flat, just above the confluence with the Clarke River. There are now 189 tunnels with two traps per tunnel in the valley, with 41 of these on the recent extension. On the last few trips it has been extremely encouraging to notice that mohua are more abundant; the results of November’s mohua monitoring confirm this abundance. We heard an average of 1.03 mohua per five minute bird count, a total of 183 mohua. This is a very positive result compared to the previous averages of 0.60 in 2002 and 0.52 in 1998. Following a beech mast in 2000 and corresponding stoat plague in 2001, stoat numbers have steadily declined in 2002/03. Seven stoats were caught over a 10 week period this year compared with 23 from the same period in 2001
NZ J. Ecology P. Dilks et al. 2003 Large scale stoat control to protect mohua (Mohoua ochrocephala) and kaka (Nestor meridionalis) in the Eglinton Valley, Fiordland, New Zealand. “Research into control techniques for stoats has been undertaken in the Eglinton Valley since 1990…Trapping proved to be effective at significantly reducing stoat predation on breeding mohua during a stoat population irruption…We set out to assess the effectiveness of controlling stoats over the whole Eglinton Valley using a low density of Fenn traps that were set continuously”
NZ J. Ecology P. Dilks et al. 2003 Large scale stoat control to protect mohua (Mohoua ochrocephala) and kaka (Nestor meridionalis) in the Eglinton Valley, Fiordland, New Zealand. “It is possible that trapping and removing stoats in the Eglinton Valley may have permitted the large increase in rat numbers there. If sustained stoat control results in a permanently high rat population, with much higher peaks than usual for areas with stoats, then this could be disastrous for the Eglinton Valley mohua population in the long term. The mohua population has already reached an extremely low level and this makes it vulnerable to chance events such as a cold winter like that of 1996. However, if we assume the rat eruption was a rare event, a result of warm winters and two consecutive beech masts, then it is likely that during “normal” years….the stoat control regime would prove effective protection for mohua”
NZ J. Ecology P. Dilks et al. 2003 Large scale stoat control to protect mohua (Mohoua ochrocephala) and kaka (Nestor meridionalis) in the Eglinton Valley, Fiordland, New Zealand. “Although rat numbers reached high levels during the beech mast in 1995/96…no predation was recorded on breeding mohua that were being monitored…in 1999 and 2000…rat numbers irrupted…this resulted in significant predation on mohua duing the breeding season and the following winter, an event not previously recorded in the Eglington Valley.”
Conservation Advisory Notes 318, 9pp. B. Studholme 2000 Ship rat (Rattus rattus) irruptions in South Island beech (Nothofagus) forest “Elliot (1990) observed that Mohua have survived for over 100 years of rat and stoat predation in beech forest where rat abundance is generally low with only occasional peaks”
Rarebits 36 DoC 2000 newsletter “The Mt Stokes mohua population has dropped dramatically. At the end of the 1998-99 summer there were around 90 birds, but now numbers are estimated at 27, of which only 6 are female. Predation by ship rats is thought to be the cause of the sudden decline. This may have occurred during winter if the birds also roost in cavities. The department had successfully increased mohua numbers on Mt Stokes to a size where the risk could be taken to establish a second population on a predator-free island. Four birds, including 1 female, were transferred late last year to Nukuwaiata. Plans to move more were scrapped when it was realised there had been a sizeable drop in the population. Seven nesting attempts were made over summer but few were successful. Cuckoo parasitism was an added problem. Intensive trapping of stoats had been sufficient to protect the birds because rats had almost never been recorded at this altitude on Mt Stokes.”
Rarebits 37 DoC 2000 newsletter “Between October 1999 and February 2000 mohua nest monitoring occurred in the Caples and Dart valleys..This was part of a stoat control study..The Caples was used as the control site, where no predator control was carried out…After a couple of weeks of ropes and mist net hauling, we managed to band around 120 birds. Nest finding provided more challenges because several pairs of birds were found building up to 4 different nests on the same day! Eventually 72 nests were closely monitored, 37 spread over two sites in the Caples and 35 throughout four areas in the Dart. Whenever possible trees were climbed to monitor nesting stages and measure nest holes. Of the total 54 breeding females, all survived the season…There was a 69% success rate in the Caples and 80% in the Dart…reasons for these nest failures including floods, abandonment, predation, and long tail cuckoo parasitism..All-in-all a thoroughly interesting and enjoyable season was had by all involved.”
Rarebits 38 DoC 2000 newsletter “Various stoat control research projects have been carried out in the Eglinton Valley since 1990. Over the past 2 years continuous, low intensity stoat control has been undertaken using Mk VI Fenn traps. Trap sites are spaced at 200 m intervals along a 45 km line that runs the length of the valley, with a short line across the valley at the top and bottom. Each of the 198 sites consists of a wooden tunnel with two Fenn traps. Traps are baited with a hen’s egg or/and a piece of meat. The trapline takes 1+ days to service and is usually checked monthly. This stoat control research is a joint project between Science & Research and Te Anau Area Office staff…Mohua: Intensive monitoring of 27 breeding pairs (38 nests) was carried out this past summer. No mohua fledged before juvenile stoats were being caught in the Fenn traps. Results: • 25 nests fledged chicks successfully • 3 failed (female OK) • 10 failed (female killed) – 6 rat predation – 1 probably falcon- 3 unknown (2 tree unclimable, 1 possible stoat/rat?) So 66% of nests fledged, 37% of females were lost but a stoat may have killed only one of these. An unusual feature of this breeding season was the high level of predation by ship rats – unrecorded in the Eglinton in previous 6 years of intensive nest monitoring. Effectiveness of stoat control: It appears that stoat control carried out at this low intensity provides sufficient protection to markedly reduce stoat predation on breeding mohua and kaka… Stoat control also appears to be effective for mohua breeding because during the 1990 stoat irruption we lost 60% of females and nests in an untrapped area. This summer we may not have lost any nests to stoats, but the huge increase in rat numbers and the associated rat predation is a major concern. The Te Anau area has had two mild winters and there is some suggestion that this results in high rat populations in beech forest. High rat numbers have been recorded elsewhere in South Island beech forests this past summer – in areas where no stoat control has been undertaken. If a permanently higher rat population were a result of continual stoat trapping, there would be serious consequences for many bird species”
Rarebits 38 DoC 2000 newsletter “quarterly mouse tracking lines and beech seed fall in the Caples and Dart Valleys have been completed. Both indices are up with mouse tracking rates averaging 43% in the Caples Valley and 73% in the Dart. Beech seed fall in the Dart is tapering off after reaching 3968 seed per square metre in March and 2336 in May this year. This is the third year that large numbers of beech seeds have been produced in the Dart.
Rarebits 38 DoC 2000 newsletter Blue Mountains mohua: 12 stoats were caught in 35,280 corrected trapnights (CTN). Over the five summers that the lines have been operated the number of stoats caught tallied 13, 6, 12, 5, and 12 respectively. Because of the extremely heavy beech seedfall of the preceding autumn and the predicted consequent mouse and stoat plague, a further three trap lines were installed in and about an area with a particularly high Mohua population. These lines were operated over November and December only and accounted for 11 stoats in 13,556.5 CTN. Given that the mouse index trapping undertaken in November 1999 resulted in a 33-fold increase in numbers caught compared with any of the preceding 5 years, the lack of a significant increase in the number of stoats caught was somewhat unexpected. Therefore one tends to the conclusion that for reasons unknown in the Blue Mountains there is a low population of stoats and/or that a stoat irruption does not necessarily follow a major beech mast year and a subsequent significant increase in mouse numbers. It’s something of a case of the more we find out the less we really know!)
Rarebits 39 DoC 2000 newsletter Mohua Rat numbers are very high in the Eglinton Valley and appear to be causing heavy predation of mohua in the Eglinton this year.
Rarebits 39 DoC 2000 newsletter Mohua: The Blue Mountains annual counts of mohua were down by between one third and one half on what would have been expected. This may have been a result of weather conditions at the time and the fact that the birds were nesting. Numbers in Western Southland..were also down on last year. However, the numbers of stoats caught in the August trapping was higher than the numbers last year.
Rarebits 39 DoC 2000 newsletter Mohua/predator control: Rat captures in the Makarora and Dart Valleys are up on previous years, and rodents now appear to be a permanent feature of these permanent trap lines. Also, in the Dart stoat numbers are increasing as a result of the mast event last spring. This is the third season in a row for high stoat numbers in the Dart. In the Catlins the post irruption survey for mohua has been started, and results so far are showing good numbers of mohua in the core.
Rarebits 40 DoC 2000 newsletter “The apparent loss of the Mt Stokes mohua has been devastating. Numbers increased spectacularly with stoat control over the past 10 years, but an unprecedented irruption of ship rats during the winter of 1999 spelt their doom. We need to learn from this experience.”
Trends in Ecology and Evolution 16: 454-459 E. Zavaleta et al. 2001 Viewing invasive species removal in a whole-ecosystem context. “species removal in isolation can result in unexpected changes to other ecosystem components …Food web and functional role frameworks can be used to identify ecological conditions that forecast the potential for unwanted secondary impacts….a holistic process of assessment and restoration will help safeguard against accidental, adverse effects on native ecosystems.”
NZ J. Zoology P. Dilks et al. 1996 The effect of bait type, tunnel design and trap position on stoat control operations for conservation management “There was a heavy beech seedfall in the autumn of 1990 in the Hawdon Valley, Arthur’s Pass National Park and in the Eglinton Valley, Fiordland National Park. The consequent stoat eruption (King, 1990) in the summer of 1990/91 provided an opportunity to assess how effectively stoat trapping can protect a native bird species (O’Donnell et al. 1996). After stoat numbers declined, trapping continued during the following summer seasons in both areas, partly to continue to protect the vulnerable mohua and also to further test baits and trapping methods.”
NZ J. Zoology C. O’Donnell & P. Dilks 1996 Control of a stoat (Mustela erminea) population irruption to enhance mohua (yellowhead) (Mohoua ochrocephala) breeding success in New Zealand “All mohua groups within or near to our study areas were monitored…a static climbing rope…allowed us to reach nests up to 32 m above the ground. The contents of nest holes were checked every 3-4 days”