Rats and other Predators

Page No. Source Quotes from Decision Documents
480 1 Agency App. F “The indirect effects of the reduction in pest numbers..on predation and the various interactions between the populations of these species [possums, rodents, mustelids] may present a direct short-term risk to some threatened species depending on the timing and level of control operations”
480 3 Agency App. F “No alternative to 1080..is available for control of rodent and stoat irruptions..1080..appears [to achieve] significant reductions through primary and secondary poisoning.”
487 5 Agency App. F “ongoing predation [during poisoning] managed by intensive trapping around nest trees”
487 6 Agency App. F “An increase in ship rat numbers..in 2000-1 [after 4 years of poisoning began in 1997] resulted in ship rat predation of 11 out of 16 [kereru] nests”
487 7 Agency App. F “counts of chaffinches, eastern rosellas, mynas and tui..increased [in a poisoned area] relative to control site”
488 2 Agency App. F “RCTI dropped..to 4.4% [one month] post operation( June 2000) rising to 9.5% in February 2002..in non-treatment area, RCTI dropped to 11.5% in February 2002, with no significant differences between treatment and control by Feb 2002.”
488 4 Agency App. F “Tunnel tracking for rats declined from 43% to 5% in the treatment area immediately after the operation and remained at </= 11% for..21 months then increased to 32% (no significant difference from control area [2 years after poisoning]”
488 6 Agency App. F “There was ongoing predation of both kaka and kereru nests..[even though] the RCTI achieved [through poisoning] (4.4%) was below that recommended for protection of kokako”
490 2 Agency App. F “[rat] tunnel tracks 44% before, 0% in Sept/Oct [after aerial 1080 in August], rising to 7% by Feb [the next year]”
490 6 Agency App. F “Four of 5 nests in the treatment area were successful (one failed due to predation) compared with 4 of 6 nests in the control block”
490 7 Agency App. F “One year after operation: fewer tomtits seen in treatment area compared to before the operation” (2000)
497 1 Agency App. F “35 [NI brown kiwi] radiotagged..one..juvenile was found dead (killed by a predator)”
498 3 Agency App. F “Predation was confirmed as the primary cause of most nest failures [of NI kokako, in areas with aerial 1080 followed by ground control over many years]
499 1 Agency App. F “Rat populations generally recovered within 3-5 months of poisoning, independent of toxicant used [during monitoring of kokako in 4 forests in the 1990’s]”
499 3 Agency App. F “Possum populations took 3-4 years to recover”
500 4 Agency App. F “Tui: significant increase on all transects; greater in the operational area than control”
503 2 Agency App. F “Continued presence of predators (rats, mice, cats, stoats) [on Rangitoto Island after 1080 cereal operation]..ongoing predation..less than expected bird population recoveries” (2004)
505 1 Agency App. F “Fifteen radio-tagged [weka]..5 birds found dead prior to the [aerial cereal] operation..4..probable stoat predation..one [re] located but not caught..1 found dead (predation) and 1 not re-located. Note: Western weka listed as being in serious decline”
506 1 Agency App. F “The Agency notes that there are indications that..possum RTCIs need to be below 5% to enable successful breeding of kereru..a target 1%..[has] been established for kokako..5% is acceptable, but more than 5% represents a failure”
506 2 Agency App. F “intensive possum and other predator management is needed to protect breeding kaka”
506 4 Agency App. F “multiple species pest control..may be required to provide protection from predation. Controlling any one pest species is likely to be inadequate”
507 1 Agency App. F “Stoats and ferrets [are the main predators of kaka, controlled by ground-based methods]”
507 2 Agency App. F “stoats [main predators of Mohua, linked with mouse irruptions]”
507 3 Agency App. F “Ship rats, stoats, possums [predators of Kereru]..ongoing predation noted after 1080 operation which achieved RTCI of 4.4% and rodent tracking index of 5% immediately after the operation..four years’ sustained ground control..including intensive trapping around nest trees..improved nesting for at least one season”
507 4 Agency App. F “Stoats, rats [main predators of Orange-fronted kakariki, only known to occur in 3 valleys in Canterbury]”
508 1 Agency App. F “Dogs, ferrets, rats, stoats, cats..pigs, mustelids, possums [predators of Brown kiwi]”
508 2 Agency App. F “Ship rats/possums, harrier hawks..mustelids [predators of NI Kokako]..sustained pest control [was considered to have increased numbers of kokako] at 3 sites”
508 3 Agency App. F “Cats and possibly rats [predators of dotterel]..intensive management [required]”
509 2 Agency App. F “increased abundance of tui and silvereyes [on Rangitoto Island 8-9 years after eradication of possums and wallabies]..the abundance of insectivorous and seed-eating birds did not increase [possibly because of] the ongoing presence of ship rats, stoats and cats”
509 3 Agency App. F “Additional seed produced [after browsing animals were removed from Rangitoto Island] may have led to increased seed consumption by rodents..[which] also consume large quantities of invertebrates, also reducing the resources available to birds”
514 2 Agency App. F “[numbers of Auckland tree weta] started declining with increases in rat and mouse indices”
514 4 Agency App. F “Treatment [aerial 1080] area RTCI <10% for at least 12 months”
514 5 Agency App. F “Treatment [aerial 1080] area <10% tracking tunnel indices for at least 12 months”
525 2 Agency App. F “kill estimates conservative due to..likelihood of immigration [of deer in year following aerial treatment of 40, 000 ha]”
526 1 Agency App. F “Mahoe [trees] showed significant improvement within a year of possum control even when possum indices relatively high”
527 9 Agency App. F “post-control [possum] densities may rise to 50% [RTCI] within 3-4 years”
531 6 Agency App. F “Other operations [rather than being based on RTCI possum numbers within the year prior to the operation]..are based on a damage threshold..and [others] on trend monitoring every 2-3 years..[when] numbers reach a trigger level, a control operation is then planned to occur 1-2 years later”
532 2 Agency App. F “The recovery of ship rat populations to pre-control levels within 2-5 months of a 1080 control operation has been noted by several authors”
532 3 Agency App. F “Mouse populations.. are reported to increase rapidly 3-6 months after reductions in ship rat numbers, peaking after approximately 9 months before declining to pre-poisoning levels”
533 3 Agency App. F “Mammalian predators are frequently killed during 1080 operations”
533 4 Agency App. F “the anticipated benefits of possum and rodent control may result in unforeseen impacts on highly valued species through prey switching, [eg] decreased rodent numbers..leading to increased stoat predation on birds”
533 5 Agency App. F “An aerial 1080 operation targeting possums and ship rats..killed all 13 radio-tagged stoats within 2-18 days of the operation”
534 1 Agency App. F “[in a ground- based 1080 operation] all radio-tagged predators (6 feral cats, 1 stoat, 1 ferret) died of secondary poisoning..all dead animals contained 1080 residues..gut contents indicated consumption of poisoned rodents or..possum carcasses..secondary poisoning of ferrets and cats scavenging poisoned rabbit carcasses has also been observed”
534 6 Agency App. F “Prey switching by cats and ferrets from rabbits to other species may occur following rabbit operations, with native skinks highly vulnerable to large swings in rabbit numbers”
548 3 Agency App. G “Tb is present in many predator populations, in particular ferrets, stoats and cats..the high correlation between Tb in domestic livestock and Tb in predators indicates that some sort of relationship exists”
551 1 Agency App. G “The applicants advise that because aerial application provides such a low density of possums relative to ground application..it takes longer for the possum population to recover to a density that requires further control”
722 2 Agency App. N “there have been instances where the use of 1080 has not been effective in effective in managing the risks of predation”
734 4 Agency App. N “The RTCI values..were 18.6..pre- and 5.6..post-operation [in a trial where bird repellent was used]; and 11.8..pre- and 9.7..[post-operation, where no repellent was used]” Post operative monitoring was delayed [for 4 months]..and may have impacted on the RTCI”
746 8 Agency App. N “Yellowhead..1 operation (cereal) Catlins Forest 1999..predation impact in 2001”
747 3 Agency App. N “Kereru..on-going predation of kereru nests [after 1080 carrot operation, 2000]”
748 7 Agency App. N “there have been instances where the use of 1080 has not been successful in adequately managing the risks of predation”
748 8 Agency App. N “Research is also in progress to further address the complexities of multiple-pest species management”
777 1 Agency App. O “aerial 1080..year 1 before treatment: 10.2..year 2 before treatment: 7..year 4: 5.7 ..[compared to control, no treatment] year 1: 16.4..year 4: 5.7” (assume figures are RTCI)
779 1 Agency App. O “achieving a target possum density of 2 possums/ha, may need treatment with Feratox every 2 years whereas aerial treatment would achieve [this] if made every 3 years”
852 1 Agency App. T: Submissions “As a landowner..I have noticed an almost complete disappearance of all living fauna after each 1080 drop. The possums, rabbits and rats are the first to recover, the birds have still not recovered.”
865 1 Agency App. T: Submissions “I am aware of the threat to these fauna [Powelliphanta snails] near my home is largely from rats, and that 1080 causes a boom and bust population swing in rats. They breed rapidly after possum competition is removed and soon pose a larger threat to snails than possums ever did”
869 1 Agency App. T: Submissions “Mustelids and cats don’t eat carrot or pollard bait, so when rodents are killed (by 1080) mustelids and cats prey on birds”
869 2 Agency App. T: Submissions “I have noticed rodent explosions months after aerial drops. Are we breeding rodents that are 1080 resistant through repeated sub-lethal doses?”
882 1 Agency App. T: Submissions “Breeding sows and boars are generally unaffected by 1080 operations and the population returns to pre-control levels within a relatively short time” (EcoFX Ltd)
898 1 Agency App. T: Submissions “A trapper in our area has found no lesions on any possums he has trapped. Other species than possums can spread Tb, and our numbers of pigs with Tb are increasing”
85 3 Applicants’ references “7-11%..of ferrets on one site and 8-15%..of ferrets at the other site apparently died of secondary 1080 poisoning [after aerial 1080 poisoning]..while we have evidence that secondary poisoning of cats does occur we monitored insufficient numbers..to reliably estimate mortality rates” (Heyward & Norbury, 1999)
90 1 Applicants’ references “NZ has a multiplicity of important ecologically challenging, animal control problems that must be seen to be believed..However, where enough soil has remained..a new and stable equilibrium of the animal-vegetation-soil complex has developed..a long-term objective toward the noxious animal problem is to strive for habitat stability” (Howard, 1965)
90 2 Applicants’ references “This study has confirmed that..rats have the propensity of developing considerable genetic resistance to..[1080] (Howard et al., 1973)
93 1 Applicants’ references “Rat populations took 4-5 months to recover..mouse tracking rates increased in poisoned forests 3-6 months after poisoning if the initial kill of rats exceeded 90%, peaked 7-9 months later then declined to pre-poison levels” (Innes et al., 1995)
93 2 Applicants’ references “Ecological consequences derive from both mammal population reduction..and..using toxins..Scientists [in NZ] have not examined the net ecological outcomes..key conservation legislation demands that [managers] do so” (Innes & Barker, 1999)
106 2 Applicants’ references “Good kill of pademelon but speculates red-necks [wallabies] come into vacated habitat” (Le Mar & McArthur, 2001)
131 3 Applicants’ references “Nine per cent of [rabbit] carcasses had been partially eaten by predators, suggesting a potential for predators to be killed during rabbit control operations” (Moller et al., 1997)
139 1 Applicants’ references “Stoats..contained mostly rats, and some birds and mice..ferrets..ate lagomorphs and invertebrates”(Murphy et al., 1998)
139 2 Applicants’ references “Stoats shifted between eating rats and birds, depending on the abundance of rats..stoats are likely to have the greatest effect on birds after successful 1080 operations” (Murphy et al., 1998)
164 2 Applicants’ references “No radio-tagged kereru and too few radio-tagged kaka bred to show [effects of possum and rat numbers after poisoning]..while no radio-tagged adult male kaka died during the study, 6 females did..radiotagged kereru suffered high mortality..predation was the main cause of mortality” (Powlesland et al., 2003)
164 3 Applicants’ references “A reduction in possum and rat densities in the non-treatment area (and increase in densities in the [1080] treatment area) meant that during the second nesting season after the poison operation, possum and rat densities were similar in the two study areas” (Powlesland et al., 2003)
185 1 Applicants’ references “The brushtail Possum..a herbivorous Australian marsupial” (Spurr, 1991)
194 1 Submitter 9074 “The [US] 1080 poisoning programme went on for a few years, until the predators and raptors were almost gone. The bald and golden eagles that had been common in the valley were seen only rarely, and hilltops that had rung with the howls of coyotes now were still and silent..Then the rodents hit the valley like a horde of locusts. With hardly any meat-eaters left to control their sharply multiplying numbers, the rodents popped up everywhere”
35 2 Committee Decision “Both DoC and Regional Councils use 1080 to control possums but the control of rats and stoats is also very important”
40 1 Committee Decision “many submitters expressed concern at the level of predation of native fauna by …possums”
40 4 Committee Decision “It was noted that aerial application of 1080 had to be well-timed with respect to the breeding/nesting periods of vulnerable species, otherwise numbers of rodents in particular may rebound rapidly (within 3-6 months of an operation)”
40 6 Committee Decision “The Committee considers that the continued use of 1080 brings the significant benefit of reduced predation of native birds”
40 8 Committee Decision “Possums and rodents also feed on invertebrates”
41 1 Committee Decision “The Committee was informed that possums have been observed preying on bats while roosting..and to eat Dactylanthus flowers which provide food..for bats and to feed on invertebrates, a key food [for bats]”
61 6 Committee Decision “The applicants explained that the lack of a dawn chorus is not attributable to 1080 so much as..ongoing predation”
132 1 Committee Decision “ten significant beneficial effects..associated with the aerial use of 1080..[include] creation of predator-free zones”
132 2 Committee Decision “ten significant beneficial effects..associated with the aerial use of 1080..[include] reduced predation [of native birds]”
132 3 Committee Decision “ten significant beneficial effects..[associated with the aerial use of 1080..[include] reduced predation [of Powelliphanta land snails]”
133 6 Committee Decision “when protecting breeding/nesting birds from predation..poor timing may reduce the benefits, and possibly require a shorter interval until next application”
865 1 Agency App. T: Submissions “I am aware of the threat to these fauna [Powelliphanta snails] near my home is largely from rats, and that 1080 causes a boom and bust population swing in rats. They breed rapidly after possum competition is removed and soon pose a larger threat to snails than possums ever did”
6 2 Submitter 9142 “[2 experiments have demonstrated that] it is very hard to reduce ferret populations for any length of time” (Ragg & Byrom review)
4 1 Submitter 9142 “After rabbit poisoning in spring, ferret home ranges tripled in size at a Central Otago site that experienced a 99% rabbit kill” (Ragg & Byrom review)