Coromandel Our Backyard

Ignorance and Unintended Consequences

It has been reported recently how four tuatara have died from eating cockroaches who were stuffed full of brodifacoum bait. This happened at Nelson “Natureland Zoo”. Remarkably, the Zoo director stated that he had not heard of brodifacoum until recently. Link to article:

Did you know that the profits of the Pest-Off state-owned enterprise Orillion ( rebranded from Animal Control Products) have trebeled since the start of Predator Free 2050 campaign? Orillion has warned the government that it will “seek compensation” , ie sue them , if their business is put at risk by any banning of pesticides. That’s why we call it “the poison-industrial complex” – a whole web of companies who are profiting from the normalisation of poisons in conservation.

Interestingly, Orillion observed in its 2018 – 2020 Statement of Corporate Intent that there are, “ continued international trends away from the use of second generation anti-coagulant products and introductions of new controls on their use.” Unfortunately too late for those Tuataras.

Brodifacoum, which had the trade-name of Talon back in the 1990s, was used all over Te Moehau and the Colville hills in an attempt to control rats. It was being used on our land too, the watershed draining into Waikawau Bay, until doing research quickly raised red flags about brodifacoum and the risk of secondary poisoning of ruru, our beloved native predator Morepork. (Note 2) Immediately we stopped using it and went further to ban the use of all poisons on our land. As providers of drinking water, we also have a responsibility to keep our watershed pure and uncontaminated. But it is still available at every supermarket!

Also brodifacoum has been found in the livers of wild pigs.( Note 3). This is concerning: many rural people depend on healthy wildlife to put food on the table, or harvesting of rongoa. The ongoing use of poisons continues all over the hills for the control of a list of unwanted species. Besides all these issues, the concern about the cruelty of these poisons is often swept aside with “the end justifies the means” mind-set.

History shows us that with pesticides and herbicides problems inevitably arise over time : persistence in the ecosystem, sublethal effects on the health of biota, and of the development of chemical resistance.(A current example is Drench resistance in sheep farming )

So it is just tragic that four of our precious ancient Tuatara were killed unnecessarily – by a lethal mix of rat poison and human ignorance.

References:

1. The only confirmed report of secondary poisoning of insectivorous birds with brodifacoum was in a zoo, where avocets, rufous-throated ant pittas, golden plovers, honey creepers, finches, thrushes, warblers, and crakes died in an aviary after feeding on pavement ants and cockroaches that had eaten brodifacoum baits (Godfrey 1985).

Godfrey, M.E.R. 1985: Non-target and secondary poisoning hazards of ‘second generation’ anticoagulants. Acta Zoologica Fennica 173: 209–212.

Source of above references: Vertebrate Pesticide Toxicology Manual (Poisons) Information on Poisons Used in New Zealand as Vertebrate Pesticides 2^nd Edition (formerly the‘Toxins Manual’) by Charles T. Eason and Mark Wickstrom, 1987 .

2. The detection of brodifacoum residues in a range of wildlife including native birds such as kiwi (Apteryx spp.) (Robertson et al. 1993), raises serious concerns about the long-term effects of broad-scale field use of brodifacoum in New Zealand. This is compounded by the recent detection of residues in a wide range of species: weka, morepork, Australian harrier, pukeko, grey duck, mallard, black-backed gull, robin, saddleback, chaffinch, mynah, magpie, and blackbird (Murphy et al. 1998; Dowding et al. 1999; G.R.G. Wright, pers. comm.)page 63

3. Murphy, E.C.; Clapperton, B.K.; Bradfield, P.M.F.; Speed, H.J. 1998: Brodifacoum residues in target and non-target animals following large-scale poison operations in New Zealand podocarp– hardwood forests. New Zealand Journal of Zoology 25: 307–314.

Dowding, J.E.; Murphy, E.C.; Veitch, C.R. 1999: Brodifacoum residues in target and non- target species following an aerial poisoning operation on Motuihe Island, Hauraki Gulf, New Zealand. New Zealand Journal of Ecology 23): 207–214.

These recently acquired residue results reinforce earlier recommendations that pigs and possums should not be hunted for human consumption, from areas where baits containing brodifacoum have been used for possum control, for at least 9 months after the application of the baits (Eason et al. 1996d).

Eason, C.T.; Spurr, E.B. 1995: Review of the toxicity and impacts of brodifacoum on non-target wildlife in New Zealand. New Zealand Journal of Zoology 22: 371–379.