Cholcalciferol

We’ve dealt with mice ever since we moved to this farm a few years back.  Mice are a bit inconvinent, but not a huge deal.  Store bags of feed in 55 gallon barrels (steel or plastic) set out a few multi-catch traps and you’re pretty much in the clear.

If only it would stay that way….

But it seems inevitable that where there is animal feed and water, there will eventually be rats. And sure enough, this winter the little scaly-tailed buggers made their way to our humble farm.

Now rats are a good bit harder to deal with than their smaller brethren.  They’re mostly nocturnal, they’re mostly subterranean and they’re an order of magnitude more cautious than a mouse.

All this means that they’re difficult to trap, shoot and exclude. Trust us, we’ve tried.

Furthermore, they seem to do a pretty good job of evading our barn cats and other natural predators.

It seems that the go-to solution to a rat problem is poison.  But as I’ve elucidated before, poison is not something I’m entirely keen on.  When you’ve got a farm full of pigs, dogs, cats and birds you’ve got to be pretty concerned about secondary poisoning.  All the commonly available first generation rodenticides I’ve seen carry a “moderate” to “high” risk of secondary poisoning for birds and mammals.

Even the “safest” second-generation rodenticide Bromethalin is making scientists skeptical of it’s safety.  It was beginning to look like that option was off the table too.

Thanks to the always-informative Michelle Canfield, I finally heard about a rodenticide that sounded like what I’ve been looking for.  Of course no stores in our area stock the stuff, but I was able to track it down on Amazon.

This stuff, Cholcalciferol (brand name: Agrid3 or Terad3) is a bait with high levels of Vitamin D3.  Rodents apparently have a very low tolerance for Vitamin D (on the order of 40mg/kg) so if they eat enough of this feed (11.5 grams of the stuff, just over 1/3rd of a block) they’ll die of a Vitamin D overdose in a couple of days.

There are studies showing that the danger of secondary poisoning is negligible to non-existant in dogs[PDF], cats[PDF] and birds[PDF]. It even seems to be what the Owl & Raptor[PDF] and Organic folks are recommending.

Safe as it may purport to be, our new “organic” rat poison is locked up in tamper-resistant bait stations.  The ever-cautious rats haven’t taken the bait yet, but we’re eager to see how it works out in the next couple of days.