Monitoring for Rodents

Monitoring almost 1,000 tracking tunnels on a 50m x 50m grid across the whole peninsula is no easy matter.

Envirokiwi were employed to run the operation, supply the coordinator and one other field operator with Glenfern Sanctuary arranging for the 6 to 8 volunteers. Scott Sambell had laid out the grid by GPS and Envirokiwi had installed most of the tracking tunnels the previous summer. Dr Emma Cronin then did an amazing job of breaking up the layout into ‘Pathways’ with each containing a series of ‘Routes’ or tracking tunnel lines that could be covered by one field operator in one day. Maps were produced for each ‘Pathway’ with the entire tracking tunnel numbers that would be encountered in the order of access. These were then laminated so they could be taken into the field.

With 16 ‘Pathways’ eight people would spend two days laying the ink cards with a peanut butter attractant in the tracking tunnels and two days collecting them. Radios were borrowed from Outdoor Pursuits Centre, Glenfern Sanctuary and Envirokiwi so that each operator, or team, could be in contact with the base operations at FitzRoy House at any time. Some of the routes on these pathways have to be experienced! To get the 50m x 50m coverage means that the contour lines can end up very close together creating some very steep cross falls. Some of the comments coming back to Base on the radios were hilarious The ground under the canopy being still very wet with a covering of leaf litter meant slipping and sliding much of the time.
 
First monitoring run

The first monitoring run was held from the 8th to the 12th of September with the Health and Safety briefing at 9 am on Day 1 when the ‘Pathways’ were allocated and maps handed out. Each operator or team then numbered all their ink cards, collected the peanut butter, notebooks, pens, markers and lunches and were sent into the bush. The Bouzaid family prepared the lunches in advance of the briefing and Gina the cook prepared hot food and drinks for when they returned often wet and sore. The Base operations officer set up scheds every 2 hours to check on positions and progress and handled queries from the field. Only one rat print was found under a house in Arthur’s Bay after the cards were returned from 906 tracking tunnels which was a magnificent result. An immediate response programme was initiated to deal with this animal.

Second monitoring run

Slip, slide slither was the order of the day over steep terrain and dense bush.

The second monitoring run was handled in the same manner as the first but being school holidays there were a lot of junior helpers. The weather was cold and overcast with heavy rain showers on two days when everyone came back drenched. After 5 days of intensive tramping no rat prints were found in any of the 906 tracking tunnels. We had enlarged Scott Sambell’s map of the ‘Pathways’ to A2 so that the base could identify where all the teams were located by radio at any time.

This is a very positive sign that the bait drops have been successful. No rabbits or pig sign but 2 instances of fresh cat scat. The next run will be early November when we will need additional help. We have to maintain this programme for six consecutive months when if no rodent sign has been found it will be phased back to once every 3 months. This will cover the build up of rats in the breeding season from November to April.

We have found evidence of rats and rabbits following the fence to the Karaka Bay end which has highlighted the vulnerability of this end of the fence. Consequently it is necessary to build a short extension from the vehicle gate to the cliff edge to redirect the pests before they have a chance to get to the fence end. However we have no funds for it!

I am really grateful to Envirokiwi, OPC, Orama, the Leys and Bouzaid families who all supplied volunteers to help make this so successful. Although FitzRoy House was in a state of absolute chaos at times it was a great team effort with a few aching muscles to let everyone know they have been out there.