PLAGUES

Source Author Year Title Quote
TV3News online 29/01/14 Simon Wong 2014 Expanded 1080 drop to curb ‘plague’ of rats “Dr Smith says it is “particularly urgent” this year because there is a one-in-10 year beech mast in which beech trees will drop a million seeds in autumn. “This flood of food will trigger a plague of an additional 30 million rats and tens of thousands of stoats,” Dr Smith says. “When the seeds germinate in spring, these starved predators will annihilate populations of our endangered birds””
Scoop Independent News 22/5/14 Murray Dench 2014 Why is there an argument over 1080? “In the poisoned block, the number of large invertebrates known to be eaten by rats soared after rat numbers were reduced to near zero, and then plummeted as rat numbers exploded to very high levels. In contrast, in the un-poisoned area, the numbers of rats and of the common large invertebrates remained more or less stable (Quote from Vertebrate Pest Research Dec 2007)”
TV3News online 29/01/14 Simon Wong 2014 Expanded 1080 drop to curb ‘plague’ of rats “The Government will be dropping 1080 poison on an extra 500,000 hectares of forest in an effort to combat an expected “plague of mice and rats of biblical proportions””
Scoop Independent News 22/5/14 Murray Dench 2014 Why is there an argument over 1080? “This year is a mast year and the Department has received around 12 million dollars in extra funding for aerial poisoning operations to limit rat populations (remember aerial 1080 does NOT kill mice). We know from the science that the operations are going to generate very large rat populations in the years following the poison drops. What is the difference between high rat numbers created by a mast year and high rat numbers created by the control operations themselves?”
Scoop Independent News 22/5/14 Murray Dench 2014 Why is there an argument over 1080? “We know that stoats eat rats, lots of rats, but their population recovery after a poison operation is delayed by a process called delayed implantation…Mating occurs in early summer, but births do not occur until the spring of the following year…This extremely long lag phase in the stoat population growth curve gives the rats a huge head start in developing a population.”
stuff.co.nz 19/2/14 Rachel Young 2014 Rat plague puts native species at risk “New Zealand’s beech forests could become like a scene from The Pied Piper of Hamelin with a population explosion of ship rats predicted this year, a senior Department of Conservation ranger says.The population boom has the potential to wipe out local populations of vulnerable species, including mohua, long-tailed bats and kakariki.”You’ll be able to come here and walk around and you’ll see rats running across the road, you’ll see rats running through the forest in broad daylight, let alone in the evenings,” said Department of Conservation senior ranger Brad Edwards.”Effectively they are going to cover the whole valley. They will chew the milking cups out of the dairy sheds, they will chew the electrics out of people’s cars in their carports, they’ll be trying to get into the houses and they will be doing all that and more in the bush.” Climatic conditions over the past two winters – a cooler one followed by a warmer one – appear to have triggered the onset of a bumper crop of seed, or beech mast…On Monday, Tinnemans checked red beech trees in Lewis Pass National Reserve. From one sample he counted 11 seed pods – in previous years this number was usually fewer than three. “This is a lot of seed. This will definitely get the rats and mice going.”
Otago Daily Times Online News 7/12/13 Rebecca Fox 2013 Beech 1080 blitz possible: Doc “A 1080 poisoning programme may be needed in Otago’s beech forests next year to protect endangered species from a potential pest plague, DoC says…staff will take samples in February, which would hopefully give an indication of the extent of seed fall and then in May results of rat tracking would show if rat numbers were rising as a result”
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 Eglington valley in Fiordland, which was reduced from several hundred to a dozen or so birds. ‘We learnt our lesson and we’ve been practicing in the meantime, so we know what to do.'”
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”
DoC Operational Report DoC 2013 Operational Report for Ship rat Control in the Lewis Pass – Station Creek 30 Oct 2012 – 07 Nov 2012 “Toxic date: 7/11/2012” [Lewis Pass]
NZ J Ecology 34: 86-114 J. Innes et al 2010 Predation and other factors currently limiting New Zealand forest birds. “Intermittent control of possums and ship rats may have the nett effect of increasing ship rats for most of the time.”
NZ J Ecology 34: 272-273 D. Armstrong et al. 2010 Impacts of pathogenic disease and native predators on threatened native species. “mice are so far the Achilles heel of many programmes, with mouse numbers irrupting following rat and/or stoat removal.”
NZ J Ecology 31: 186-201 P. J. Sweetapple & G. Nugent, G. 2007 Ship rat demography and diet following possum control in a mixed podocarp-hardwood forest “Mean ship rat abundance indices increased nearly fivefold after possum control and remained high for up to 6 years…the typical outcome for most pulsed possum control is an uncontrolled ship rat population in the presence of a low-density possum population for most of the 3-7 year cycle.”
Conservation Advisory Notes 318, 9pp. B. Studholme 2000 Ship rat (Rattus rattus) irruptions in South Island beech (Nothofagus) forest “Craigieburn Forest Park is another area where rats have only recently been detected.”
Biological Invasions D. Towns et al. 2006 Have the harmful effects of introduced rats on islands been exagerated? “What a poor, curtailed, mutilated sterile world we threaten our descendants with! Man and the rat sharing it – fit mates in many ways – in their desperate, deplorable, gnawing energy, in their ruthless desctruction of every obstacle.” (Guthrie-Smith 1936: 218 on the lost fauna of the sub-antarctic islands)”
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…Following a beech mast in 2000 and corresponding stoat plague in 2001, stoat numbers have steadily declined in 2002/03.”
Rarebits 55 DoC 2004 newsletter “Catlins: We received money for stoat control but while in the process of preparing an operation plan, issues concerning rats arose; an observed doubling of rat abundance occurred between the start and end of October.”
Rarebits 50 DoC 2003 newsletter “We continue to have elevated numbers of mice in tracking tunnels and traps in the Catlins mohua areas. A number of rats have also turned up. As we did not have a beech seedfall event last autumn, the jury is out on what is happening and whether it will lead to a stoat eruption”
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.”
Rarebits 44 DoC 2002 newsletter “Over the last six seasons, mohua productivity and numbers were increasing as a result of stoat control, however rat plagues are a new phenomenon for DOC in the South Island with swift and catastrophic impacts.”
Rarebits 46 DoC 2002 newsletter Mice continue to demonstrate their tenacity, or maybe toxin tolerance, by persisiting on Mokoia Island in Lake Rotorua, and Limestone Island in Whangarei Harbour. In both instances, it is despite two or more very determined eradication attempts. They (mice) quickly reach such low levels as to be impossible to detect, only to be re-detected five or six months later in the odd tracking tunnel. Normal pattern then, is for the place to soon become overrun with the critters.”
Rarebits 46 DoC 2002 newsletter “Okarito Kiwi Zone: The results from the rodent lines in March show that there has been a huge increase in rat abundance between March (3.5% tracking index) and August (80% tracking index). This correlates with our casual observations from the stoat trapping program which have indicated a much higher rat trapping rate than previously. We have also been noticing the capture of lactating female rat’s right throughout the winter months. It seems that rat numbers are higher within the sanctuary (80% tracking rate) as opposed to in the two areas in which do not have stoat trapping (38.6%) although this will not be confirmed until the November tracking session is completed. It will be interesting to see whether stoat numbers increase this summer in response to the increased rat abundance and if so how effectively the trapping program deals with this increase…Since May 2001 there have been a total of 605 stoats caught.
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…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 36 DoC 2000 newsletter “The Mangatutu kokako protection project has just finished its fifth breeding season and things are looking very encouraging in the Mangatutu Ecological Area. All the pest control continues to be successfully carried out by Laurence Gordon and the odd volunteer under his supervision. Laurence services somewhere in the vicinity of 1000 bait stations and has recently completed a very thorough and comprehensive track marking and mapping exercise, which will enable volunteers and future workers to find every bait station! This summer Laurence got rats to low levels despite apparent rodent plagues in many parts of the country”
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…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…To keep the stoat population at a low level with a low density of traps probably requires continual trapping. Further work is needed here on rat population dynamics in beech forests to determine whether lack of predators means a larger irruption in mast years or if climate is the major influence.”
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 38 DoC 2000 newsletter “The carrot-1080 aerial possum poisoning operation occurred in May 2000. The prefeed baits were distributed at 5 kg/ha by the contractor, Epro Ltd of Taupo, on 1 May. The poison bait (10 kg/ha, 0.08% 1080, 2435 ha treatment area) was distributed on 17/18 May…Monitoring was repeated in the treatment area following the poison operation (12-16 June 2000)…The mouse index declined in the non-treatment area (30 to 14%), but increased in the treatment area (23 to 30%).”
Rarebits 39 DoC 2000 newsletter “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/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.”
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.”
Rarebits 40 DoC 2000 newsletter “Trap lines for stoats in the Makarora Valley continue to catch stoats. Recently numbers are dropping off, and the rate of rat captures is increasing slightly.”
NZ J Ecology 23: 95-100 N.C. Alterio et al. 1999 Trappability and densities of stoats (Mustela erminea) and ship rats (Rattus rattus) in a South Island Nothofagus forest, New Zealand “Fluctuations in trap success suggest that stoats become very numerous in the summer and autumn following heavy seedfall, but remain at low abundance in the intervening times.”
NZ J Ecology 23: 95-100 N.C. Alterio et al. 1999 Trappability and densities of stoats (Mustela erminea) and ship rats (Rattus rattus) in a South Island Nothofagus forest, New Zealand “Mice may also prey on eggs and the role of weasels in killing adult and young birds is unknown. Accordingly, predator control operations should target all these predators to minimise predation risks to native wildlife, at least until the relative impacts of each species has been discerned”
NZ J Ecology 19 (1): 5-17 J. Innes et al 1995 Large-scale poisoning of ship rats (Rattus rattus) in indigenous forests of the North Island, New Zealand “Unexpected ecological repercussions of large-scale poisoning in North Island New Zealand may include a functional change (diet) by stoats and a numerical change (increase) by mice. Assessment of the costs and benefits of large-scale poisoning must allow for these and other repercussions of community perturbation.”