By Alison Campbell 09/10/2017 2


Kerikeri award entry turns possums into burning issue“, proclaims a headline in the Northern Advocate. 

The story is about an entry in the WWF-NZ’s Conservation Awards for 2017; I hope the judges have a good grasp of science and scientific method. From the article:

The entry from Kerikeri promotes a new take on an old-world biodynamic method of ridding fields of rodents and other furry pests.

It is called peppering, and involves burning the pelts and carcasses of said pests until they’re little more than ash, grinding it finely, mixing it with water and “spray painting” the substance back on the affected land.

Apparently, this version of the ‘traditional’ practice is

new in the sense that so far it has not been applied because it lacked ‘scientific background’.

And it still lacks that background; using a drone to disperse possum ash doesn’t make the practice any more scientific.

This is something I first wrote about back in 2010. As I said then, there’s no plausible mechanism by which ‘possum peppering’ might work (vague appeals to ‘energy forces’ don’t count). The anecdotal claim cited in the Northern Advocate, that the stuff is ‘effective’, is presented in the article without evidence. However, science has already tested that claim:  back in 1992 Eason & Hickling summarised their controlled experiments thusly:

Bio-dynamic control involves burning pest tissue or organs and spreading the ash on areas to be protected. In New Zealand, bio-dynamic methods have been suggested for repelling possums where they damage forests or spread disease. We assessed the repellent effects of five bio-dynamic tinctures. First we tested these materials on possums in pens and noted their effects on foraging behaviour, food consumption, and body weight. Then we monitored bait consumption from treated and untreated feeder stations in the field. Although an orthodox herbivore repellent significantly deterred possums, we detected no behavioural or repellent effects of the biodynamic tinctures in any of our trials. We are unable to recommend these tinctures for possum control.

The saddest part is that the native forests in Northland are already collapsing under a combination of pressure from introduced pests such as possums & chronic shortage of funds for conservation operations in the region, and opposition to the use of 1080 isn’t helping things. Suggesting pseudoscientific woo as an alternative is hindering rather than helping those doing their best to ensure the survival of these forests and the native species dependent on them.

Eason, CT & Hickling, GJ (1992) Evaluation of a bio-dynamic technique for possum pest control. New Zealand Journal of Ecology 16(2): 141-144

Featured image: Wikimedia / Andrew Mercer.


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