1. Friends of Puketoki Reserve Improving forest health and restoring native birdlife
2. Background Located 20 minutes from Tauranga, on Leyland Road, off Whakamarama Road, this attractive stand of native bush is located in the upper catchment of Te Puna Stream. An old bush tramline, which forms part of the track system, is evidence of the early activities of the Whakamarama Land & Timber Company. Mill manager Henry Sharplin donated the reserve to the people of Tauranga County as a scenic reserve in 1926 and since then it has been a popular walking and picnic spot. Mature tawa and the occasional mature rimu dominate the reserve and the tracks are well developed with stream crossings bridged.
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4. Pest Tracking Trackers were placed on all six lines at 50m spacings (totalling 35 tunnels). A non-toxic lure was placed within the tracking station – usually peanut butter – to attract rodents and other animals. The animal walks across an ink ‘tracker’ and as the animal leaves its footprints are left. The trackers are left overnight and recovered by volunteers the next day. Initial results at Puketoki showed a significant presence of rats and mice. Bait interference has been an ongoing problem within the reserve and an ‘open’ set of tracker cards placed in front of a bait station confirmed our suspicions - hungry possums (bottom set of photos) were raiding the rat bait which didn’t effect them.
5. Vegetation Survey Vegetation plots were established within the reserve in 2006 and were resurveyed in April 2007 after nine months of animal pest control. Vegetation surveys were completed to give a general indication of species regeneration. Mature tawa and the occasional mature rimu dominate the reserve, with a reasonably diverse under story comprising of 51 species or more as recorded in this survey. Six 5x5 meter vegetation plots were established at Puketoki Reserve on the 20th of June 2006. These plots were surveyed again on the 17th if April 2007 to establish any changes in species regeneration. The number of seedlings, saplings and trees were recorded for each species (Table 1). Table 1: Classification of forest structure Each plot was established next to the different bait lines. 5cm to 45cm high Seedling 45cm to 135cm high and less than 3cm diameter Sapling Greater than 3cm diameter at 135cm above the ground Tree Measurements Classification
6. Figure 1: Overall vegetation species abundance for 2006 and 2007. Vegetation Survey Results
7. Vegetation Survey Discussion The vegetation surveys were conducted by Jennifer Murray, a recent from BOP Polytech, who has been working on similar projects for Environment Bay of Plenty. Most of the above species are regenerating well and the fact that Alseuosmia is present, let alone being one of the species with an increase in % seedlings, indicates good regeneration. This is usually a sign that possum are not abundant which contradicts evidence from other observations, particularly the high level of bait interference and territory marking. Kohekohe seedlings were also showing signs of possum damage. The overall results showed that tawa ( Beilschmiedia tawa ) had the most significant increase in seedling abundance. This is probably due to the fact that these seedlings were present in 2006, but were under 5cm and therefore not recorded in the survey. Most of the above species are susceptible to possum or rat interference, by either seeds or seedlings being eaten. At present these species are still regenerating slowly and with pest control they should recover fully.
8. Rodent Control Results Ditrac bait has been used for rodent control throughout the operation, placed within plastic tube bait stations purchased through Environment Bay of Plenty. Each station holds 3 baits and were placed along 6 lines in the reserve. There were 40 stations in total. At first the baits were taken slowly, then regularly at and around the 100% mark. In total 4024 baits were taken out of 4098 baits laid.
9. Rodent Control Discussion Ditrac bait has proven to be an effective bait for rodent control in many other pest management programmes and seasonal monitoring with trackers confirmed that we had few rats by spring 2006. The fact that bait take continued unabated, coupled with increasing bait station intereference, lead us to the conclusion that bait was being raided by possums. We tried a number of methods to confirm this belief including looking for possum sign, spotlighting, wax tags and Striker prefeed baits. None of these methods indicated high densities of possums but the bait kept disappearing, often within 48 hours. The tracker configuration shown in slide 4 confirmed our suspicion. We collected good sets of possum prints at four different bait stations within 24 hours of placing baits in the stations, and the marking indicated the process they used for clawing out the baits. Recent rodent monitoring (February and late March) indicated that the rat population remains extremely low so we assume that rats have still been able to access some bait. A number of possum control options have been discussed with EBOP pest animal officers, from cyanide (Feratox) to brodificoum (Pest Off) but there are drawbacks to both (and significant constraints to the former). Two experienced contractors visited the site recently and have decided to set up a pilot project using a few new products to test their effectiveness in this kind of setting. The costs will be met by Connovation Ltd.
