Independent scientific reviews

and official documents on 1080

1080 causes rat plagues and increased mouse numbers

date	authors	source	name	quote
2016	Griffiths, J.W., Barron, M.C.	NZ J Ecol. 40 (3)	Spatiotemporal changes in relative rat (Rattus rattus) abundance following large-scale pest control	“Population control of rats appeared effective with few to no rat tracks recorded in treatment areas for 6 months after the aerial application of 1080. However, rat tracking indices increased rapidly after that, and in 24-30 months after 1080 application rat tracking indices in treated areas exceeded those in the non-treatment area.”
2016	Griffiths, J.W., Barron, M.C.	NZ J Ecol. 40 (3)	Spatiotemporal changes in relative rat (Rattus rattus) abundance following large-scale pest control	“After a delay, growth in rat tracking indices was highest in the interior of treatment areas and negative in the uncontrolled areas, leading to peak rat tracking indices in the treatment area exceeding concurrent indices in the non-treatment area. These results align with those of other studies that monitored relative rat and possum abundance following pest control.”
2015	Kemp, J., Cunninghame, F., Barrett, B., Makan, T., Fraser, J., Mosen, C.	Released under the Official Information Act (unpublished)	Effect of an aerial 1080 operation on the productivity of the kea (Nestor notabilis) in a West Coast rimu forest	“Mouse relative abundance at Okarito increased following the 1080 operation and then declined again as rats repopulated. Rats at Fox-Paringa [not treated] showed a natural post-irruption decline, or crash, during the winter of 2012 and remained low through 2013. In contrast, rat abundance at Okarito increased during 2012 and stabilised at moderate-high levels during 2013.”
2010	Innes, J., Kelly, D., Overton, J. McC., Gillies, C.	NZ Journal of Ecology 38(1): 103-109	Predation and other factors currently limiting New Zealand forest birds	“the timing and frequency of pest control also influences the outcome. Intermittent control of possums and ship rats may have the nett effect of increasing ship rats for most of the time
2013	Nugent, G. & Morriss, G.A.	NZ Journal of Ecology 37(2):246-255	Delivery of toxic bait in clusters: a modified technique for aerial poisoning of small mammal pests	“there are major ecological complexities, in that possum control alone can result in increases in ship rat (Rattus rattus) densities (Ruscoe et al. 2011) with adverse consequences for native invertebrates (Ruscoe et al. 2013).”
2011	Veltman, C. & Westbrooke, I.M.	NZ Journal of Ecology 35(1): 21-29	Forest bird mortality and baiting practices in New Zealand aerial 1080 operations from 1986 to 2009	Ship rat populations at some times recover rapidly from very low densities after 1080 poison operations, to reach densities (indexed by kill-trapping) higher than existed in the presence of possums before control was carried out (Sweetapple & Nugent 2007).
2011	Ruscoe, W.A., Ramsey, D.S.L., Pech, R.P., Sweetapple, P.J., Yockney, I., Barron, M.C., Perry, M., Nugent, G., Carran, R., Warne, R., Brausch, C. & Duncan, R.P.	Ecology Letters 14:1035-1042	Unexpected consequences of control: competitive vs. predator release in a four-species assemblage of invasive mammals	Rat numbers declined immediately following the poison operations (Fig. S3) but by year 1 post-treatment rat numbers in the possum and possum + rat removal treatments were similar to the control…relative to the control, rat numbers had increased significantly by year 2 in the possum removal treatment, such that rats were almost twice as abundant as at the control sites, consistent with competitive release of rats following possum removal.”
2011	Ruscoe, W.A., Ramsey, D.S.L., Pech, R.P., Sweetapple, P.J., Yockney, I., Barron, M.C., Perry, M., Nugent, G., Carran, R., Warne, R., Brausch, C. & Duncan, R.P.	Ecology Letters 14:1035-1042	Unexpected consequences of control: competitive vs. predator release in a four-species assemblage of invasive mammals	“unlike other multi-trophic assemblages of invasive species where top-down regulation limits mesopredator abundance (Courchamp et al. 1999),rats, the most abundant mesopredator in our four species assemblage, appear to be more strongly regulated by food availability. Consequently, removal of a key competitor, possums, which is done routinely to reduce browse damage and the spread of bovine tuberculosis in New Zealand forests, leads to an unintended and potentially damaging outcome: more rats. Given the known negative impacts of rats on native biota in New Zealand, and elsewhere (Towns et al. 2006; Gibbs 2009), the benefits associated with possum control need to be weighed against the consequences of increased rat numbers.”
2011	Ruscoe, W.A., Ramsey, D.S.L., Pech, R.P., Sweetapple, P.J., Yockney, I., Barron, M.C., Perry, M., Nugent, G., Carran, R., Warne, R., Brausch, C. & Duncan, R.P.	Ecology Letters 14:1035-1042	Unexpected consequences of control: competitive vs. predator release in a four-species assemblage of invasive mammals	“The dominance of competition over predation as a regulatory process in our system highlights the potential for unexpected effects beyond release from predation when manipulating multi-species assemblages of invaders.”
2007	Sweetapple, P. & Nugent, G.	Kararehe Kino 11:Dec	Secondary Effects of Possum Control	“individual pest species are part of an interacting web of both exotic and native plants and animals, so the reduction of one pest species may have unexpected outcomes for other pest species and their impacts. For example…reduction of rodent populations can lead to increased predation of native birds by stoats, while possum-only control can lead to sustained increases in rat abundance. The consequences for native ecosystems of such unexpected outcomes are poorly understood.”
2007	Sweetapple, P. & Nugent, G.	Kararehe Kino 11:Dec	Secondary Effects of Possum Control	“At Mokau, possum control in 2002 using aerially sown 1080 baits reduced possum and rat populations to near zero…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 unpoisoned area, the numbers of rats and of the common large invertebrates remained more or less stable.”
2007	Sweetapple, P. & Nugent, G.	Kararehe Kino 11:Dec	Secondary Effects of Possum Control	“At Waihaha, possum numbers were first reduced to low levels in 1994. This resulted in a sustained 4-5 fold increase in rat abundance. Possum control was repeated in August 2000 using aerially sown 1080 baits and provided effective rat control for about a year before their numbers rose to the high levels seen prior to August 2000…Robin encounter rates rose dramatically during the two breeding periods characterised by low or increasing rat abundance, before steadily declining to pre-August 2000 levels once rat numbers peaked…Ground invertebrates were also numerous while rat numbers were low, but invertebrate numbers fell once rat populations started to recover.”
2011	Jones, C., Pech, R., Forrester, G., King, C.M., Murphy, E.C.	Wildlife Research, 38: 131-140	Functional responses of an invasive top predator Mustela erminea to invasive meso-predators Rattus rattus and Mus musculus, in New Zealand forests	“Management of this suite of introduced species [in NZ] needs to avoid cascading threats when eruptions of rodents lead to more stoats (e.g. King 2002), perverse outcomes when removal of ship rats results in more mice (e.g. Innes et al. 1995, Tompkins and Veltman 2006), and take advantage of trophic interactions, e.g. when control of one pest species also reduces the abundance of their predators through loss of prey or secondary poisoning (e.g. Murphy et al. 1998).”
Accessed 2015	Byrom, A., Banks, P., Dickman, C. & Pech, R.	Landcare Research. Available at landcarereserach.co.nz/publications	Will Reinvasion Stymie large-Scale Eradication of Invasive Mammals in New Zealand?	“Species interactions: There is now substantial evidence that interactions among invasive species need to be taken into account in control programmes. For example, in North Island forests control of ship rats leads to greatly increased abundance of house mice (Ruscoe et al., Kararehe Kino, Issue 13)