The rodent control aspects of our project has 26 lines of bait stations (each ~9), plus one line of A24s. For the bait stations we report bait take and number of stations emptied in each pulse. For the A24s we report number of kills reported (not bodies sighted). There are opportunities for measurement error with both systems.
My question is, how can I combine these reports in order to report for the project overall? Does anyone know of an estimate of how much bait take (Contrac 28-gram blocks) yields one dead rat so I can convert bait take to estimated total rat deaths? Or an estimate of A24-reported kills to actual kills?
The Contrac 28g “Blox” have 0.005% Bromadiolone as the active ingredient.
Its an old (1980) study but page 3 of this suggests that healthy rats died from eating between 3 to 18mg of active ingredient per Kg of body weight.
By my calculations there is 1.4mg of active ingredient in each block - If we say an average rat is 250g
then 0.775 to 3mg of active ingredient is required to kill one Rat.
The Contrac technical info sheet explains that one bait is enough to kill one rat (presumably taking an “average” rat size). You maths sort-of confirms that.
But my question was how to combine counts for reporting purposes. I have a set of baitlines, & have been reporting bait take per baited station. But one line is now in A24s, so the data we have are strikes instead of baits.
I can convert all to estimated rats killed, but saying eg 32 baits taken is not the same (on average) as 32 rats killed as the rats live for some days before succumbing, and presumably some eat some more yummy dinners in the interim. And some of the bait take is by mice or smaller critters.
I was wondering if anyone has studied or estimated the actual number of baits eaten per rat killed.
There are similar issues with the A24 counts, but I haven’t yet got my head around them! I guess a strike does not necessarily mean a kill, so how many kills is likely if there are say 8 strikes?
Thanks for the thoughts,
j