That is exactly what happens. Hence Mintie's comment about the possum numbers in HB being on the rise.
Once the blocks are rolled out of the Tb Free program it is up to the council with the farmer self help program. They monitor farms randomly but there are too many to really get around. Whilst some farmers are doing their part some others aren't and some forestry companies are not either.
The other problem is that landowner's without a CSL don't have many options when it comes to filling bait stations and the council really push the use of brodifacoum, which in reality is horrible shite.
Problem is from memory a possum it takes approximately 100 grams of pest off to kill a possum, a sentry bait station doesn't hold all that much bait. So if 3+ possums visit that station then unfortunately there is a chance that they will all just receive a sub lethal dose. People don't have the spare cash to potentially need the stations filled more that once per year so it is what it is.
Bookmarks