Pest control in local forests

Forest and Bird, Issue 292, 1 May 1999, Page 42

Pest control in local forests

South Waikato branch has developed a pest control programme which doesn’t need a MAF poison licence.

Oo you, your neighbours or have a backyard or area of bush that needs protecting from introduced pests? Gordon Stephenson and the South Waikato branch have produced a simple guide to pest control based on experience at their Waotu project. They emphasise that while their programme has been developed over the last eight years they are still learning from their experiences. Nevertheless, they are achieving good results. The control programme for possums and rats will also produce some by-kill of other pests such as mice. South Waikato Forest and Bird uses this timetable: Step 1, June-July: Assume possum density is about 12-15 per hectare, plus mice, rats, mustelids, feral cats. Invite a professional possum hunter to take the ‘first cut, which should drop numbers to about five per hectare. This part is the most profitable to a hunter, and the most expensive for a bait station programme. Step 2, August: While numbers are still low, and before breeding, establish the bait stations. There are then three options: (a) bait stations at 150-metre intervals (one per 2.2 hectares) gives excellent possum control and gets about 80 percent of rats; (b) stations at 100-125-metre intervals gives excellent control of possums and rats; (c) stations set along ridges and tracks at 150-200 metres, gives reasonable possum control if the programme is long-term. Place stations about 15 centimetres above ground, or in a tree fork to avoid poisoning ground-dwelling pets, etc.

Step 3, August-November: Place brodifacoum (Talon or similar) pellets in stations. Begin with up to one kilogram per station. Recharge once a month (e.g., first weekend of the month). Do not keep filling up stations between times — it is wasteful, with little benefit. By October, 250-500 grams of bait should be ample. Step 4, December or January: Stop baiting. Clean the stations to stop old bait going mouldy. Do not rebait until making another ‘pulse’ in April-May. Stop baiting again in June-July. Our experiences with this programme have produced a number of useful tips: @ The programme, using options (a) or (b), should give good or total control of possums and rats. If conditions are very wet, the ‘waxed egg’ bait

Talon 50 WD is moisture-resis-tant, but it is twice the price. @ There should be some by-kill of mustelids and wild cats feeding on dying possums and rats. @ The two periods of ‘non-bait-ing’ allow some build-up of rat numbers to obtain a by-kill and assists in avoiding ‘bait-shyness’. The rest period also helps reduce the total amount of poison used, as concerns exist about the persistence of brodifacoum in the environment.. @ With a programme in one portion of a large area of forest, a barrier of a line of stations at 50-metre intervals at the outer edge of the baited area will assist in preventing re-invasion. @ Brodifacoum is an anti-coagu-lant, and the antidote is Vitamin K. (See a vet., in the unlikely event of poisoning a pet.)

To catch mustelids

Use Mark 6 Fenn traps in tunnels 180 millimetres high by 150 millimetres wide by 750 millimetres long. Preferably two traps per tunnel with a bait (a cracked egg, fresh meat etc) between. Place alongside fence, track or a log.

Capturing wild cats

Try Timms traps with entrance enlarged by one centimetre in diameter. Pre-bait with meat scattered around trap for two or three nights, then set trap with meat.

Discouraging rabbits, hares

Rabbits eat leaves, dig up roots. Hares cut off stems with a neat 45° cut. Try soaking natural fibre baling twine (not synthetic) in creosote, and lay in a circle around young trees.