The KNE Small Mammal Monitoring programme targets rodents (rats and mice), mustelids and hedgehogs. This is done using tracking tunnels, following the DOC protocol, with two exceptions:
We report on the standard error (SE) as this is a measure of how accurately we are estimating the actual tracking tunnel index for each site using the tracking tunnel lines we sample.
Note that field designs were set up using the latest version of the DOC protocol available at the time of establishment.
Table 1: Monitoring schedule summary for the KNE Small Mammal Monitoring programme. The dashes indicate this site is not directly sampled for that species.
| KNE site | Rodent monitoring | Mustelid & hedgehog monitoring | Lizard monitoring |
|---|---|---|---|
| Wainuiomata/Orongorongo | Feb, May, Aug, Nov | Nov, Feb | - |
| East Harbour Northern Forest | Feb, May, Aug, Nov | Nov, Feb | - |
| Baring Head/Ōrua-pouanui | Feb, May, Aug, Nov | Nov, Feb | Nov, Feb |
| Belmont Korokoro | Feb, Aug | Feb | - |
| Queen Elizabeth Park | Feb, May, Aug, Nov | - | - |
| Western Wellington Forests – Otari/Wilton's Bush | Feb, Aug | Feb | - |
| Western Wellington Forests – Johnsonville Park | Feb, Aug | - | - |
| Porirua Western Forests | Feb, Aug | - | - |
Rodent monitoring takes place over one dry night. The rodent tracking tunnel index (TTI) for each area is calculated as the percentage of tunnels that rats or mice were tracked at along each line of tracking tunnels. This is averaged across the lines monitored at most of the KNE sites to give a TTI for the area. At Otari/Wilton’s Bush however, tracking tunnels were established on a grid and the TTI is calculated as a percentage of the total number of tunnels tracked.
Note that the tracking tunnel method only provides a coarse index of the relative abundance of rodents and is not a direct measure of their population density. The method is best suited to comparing:
The relative abundance of rats is compared to management targets that have been set for the various KNE sites. For the Wainuiomata Mainland Island and East Harbour Northern Forest Mainland Island the target is a TTI of no more than 5 percent. For all the other KNE sites the target for rats is a TTI of no more than 10 percent.
No target is applied to mice because of the difficulty in controlling mice populations. Controlling rat numbers is considered to be more important than mice populations for protecting bird populations. Mice populations can also increase when rat numbers are controlled due to decreased competition for food and predation by rats.
Rodent tracking can give highly variable results, particularly where there are low numbers of monitoring devices. Consequently, these targets should be considered as aspirational rather than definitive. Management decisions should consider the degree of population change, time-of-year, or the prediction of a coming mast season.
Mustelid and hedgehog monitoring takes place over three dry nights in February and November at some KNE sites. Mustelid and hedgehog tracking percentages are calculated based on the percentage of all the tunnels tracked in the monitoring area that these pests were encountered in, irrespective of tracking line. Unlike the rodent monitoring, this provides a single, un-replicated sample for each monitoring area. Hence the standard error (SE) cannot be calculated for the relative abundance of mustelids or hedgehogs.