Attractive palatable baits
Bait for long enough to ensure all animals encounter bait
Bait at times when animals are not breeding and natural food is short
Where possible rotate baits annually
Monitor pests and desired outcomes
Adapt to observed conditions
For possum control the ideal grid is 100m x 100m given enough time and providing the baits are kept fresh. You may also want to try pre-feeding a couple times and mapping where you get most of your activity with a view to boosting bait station numbers in areas where there is a lot of activity. If your policy allows brodifacoum, then you could use this as a mop up tool. Use small amounts i.e. about 500 gms, check regularly, ensure none is left spilt anywhere and make sure it is changed before going mouldy. If there are pigs being hunted in the area let the hunters know about the consequences. Pigs will also get onto lines, break bait stations and generally cause havoc.
Another follow up method would be to pre-feed twice – place extra stations in areas where they may be concentrations of activity. I would suggest fill in at 50m intervals if you are planning to attempt localised rat eradication in the future or place at 75m to bisect current grid lines and go for a lower, probably single figure 4-6 rat index. Use Feratox as the possum toxin and use a registered anti-coagulant for the rats. When we were undertaking the diphacinone trial work we had a lot of possum take on the rat bait in South Westland. We inserted feratox into the diphacinone paste and removed 62 possums over 5 weeks from one bush clad edge of a 40 hectare treatment plot. The rats were also killed.
Feracol can be used. Pre-feeding is required and rats are either killed or deterred by the feracol leaving plenty for the possums. Feracol should be used in a rotation with other products. 1080 and feracol can both lead to bait shyness if overused. Another key element is boundary control. You may need to place more emphasis on boundaries that harbour large numbers of possums or rats. Possum kill traps can be used for boundary lines – spaced at 50 – 100 metres. Look for trees that have a lot of sign as the possums will frequent certain trees more readily. The Warrior kill traps are a good choice for this type of work.