The Green Room
The Environmental Protection Authority has approved the import and manufacture of a new poison - Zinc phosphide - to control possums. Unlike 1080 poison it has only been approved for ground control, but it is still has potential to be a vital new addition to the pest control agencies' toolkit.
http://www.scoop.co.nz/stories/PO1108/S00142/zinc-phosphide-pest-poison-approved-with-controls.htm
If you can tell me that Zinc Phosphide not only kills possums but that the dead possum goes on to kill the stoats that eat the dead possum through a secondary kill then whoopee!! We might have a tool that is as conservation effective as 1080 or brodifacoum.
Otherwise it will join the arsenal of self re-setting traps, cyanide, racumin and all the other "tools" that have been developed by those who don't seem to understand that pest control ecology is about interconnections.
In the cold middle of winter or early spring, if you are a carnivore such as a stoat you are foraging everywhere for fresh or decomposing food. You have a high metabolic rate and have to eat frequently to stay alive and active. It is one of the reasons why in colder climates than ours, many of these carnivores hibernate. This reduces their need for food in the leanest time of the year.
In the NZ winter, along comes a possumer using cyanide or a trap or any one of the other baits that are being developed that don't give a secondary kill.
The possum dies and its body is left lying on the forest floor. Alternatively the possumer taking fur or skins takes them off the possum then drops the naked possum to the forest floor.
In all cases they are providing a wonderful welcome protein food source for the hungry stoat. It may well make the difference between that stoat dying out that winter or surviving to kill baby birds in the spring.
Ecologists Odum & Odum wrote a wonderful book Ecology that explains Food Chains. Stoat are part of a food chain and when their main food, the mice and even rats have died off in the cold winter, stoats will be looking everywhere for fresh food. A dead, non toxic possum carcasse is just what the doctor ordered.
If we understand this eventually DOC and other land managers might insist that all possum caarcasses killed through trapping or non secondary kill poisons are carried out of the bush.
If you don't believe stoats eat dead possums, drive down any West Coast highway littered with road kill possums. You will see stoats running away from feeding on the carcasses.
Ertvakie please assure me that zinc phospide does give a secondary kill?
Hi Tawaki. I'm not the expert, just the messenger. My personal opinion is that it is very misleading to describe MZP as an 'alternative' to 1080 when it cannot be used aerially. In terms of it's secondary poisoning potential, it doesn't sound too encouraging really. I found this on an Australian website:
"Studies investigating the potential secondary poisoning and non-target effects of zinc phosphide grain bait formulations have found that bait posed little hazard to non-targets if applied in-crop when sufficient food was available. To date, evidence shows minimal non-target impact from zinc phosphide grain bait use."
Source: http://www.dpi.qld.gov.au/documents/Biosecurity_EnvironmentalPests/IPA-Zinc-Phosphide-PA3.pdf
I also know that the Animal Health Board does not consider it to be an alternative to 1080 http://www.ahb.org.nz/Default.aspx?tabid=213
This 2009 study http://www.doc.govt.nz/upload/documents/science-and-technical/drds312entire.pdf by Charlie Eason is also a good source of information on the toxin. This, too, mentions "the comparatively low risk of secondary poisoning following its field use'
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