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Rat tracking - bait at the ends or the middle?

I was interested to hear at the 2011 Sanctuaries Workshop at Nelson that some folks were still confused about whether they should bait tracking tunnels for rodents (mainly ship rats) at the ends or the middle.  It seems to me that there is no substantial real issue here, and it may help to explain why.

The key matter to resolve is: why are you undertaking the tracking in the first place?

The main conclusion is clear:  if you want to ‘plug in’ your rat outcomes to published accounts of benefits, such as kokako nesting success, then you should use the current DOC protocol verbatim, ie bait at the ends.

I should note though, that the widespread use of the 5% target for rats and possums for ecosystem recovery is just a somewhat wild stab in the dark as a target.  That is, the benefit of this target cf any other is as yet unpublished, as far as I know.  It’s as good as any other smallish number, and it is substantially smaller than what you will get if you do no population control, but it has no published relationship with ecosystem health at present.  So violating the SOP tracking measure in ecosystem restoration is just adding a bit more uncertainty to an already uncertain relationship between index and outcome.

John Innes

Landcare Research, Hamilton

6 September 2011.