Chew-sing where to target our predator control: 9 Years of the PFK Chew Card Campaign – 2026 Results
Updated: 8 minutes ago
Chew Card Results Presentation Night 08/09/26
Ngā mihi nui to all our volunteers! Thank you to those who took part in the survey and those who came to the presentation night to see the results. Every year since 2017, monitoring cards have been placed out in 44 different reserves, along 92 different monitoring lines. 2026 was another successful year of data collection, with 36 reserves and 68 lines.
Why do we monitor?
Monitoring results help to identify current predator relative abundances within each monitoring line.
The results allow for more effective and precise future predator control efforts. Results also allow us to track general progress of past/current control from reserve volunteer groups.
Allows us to compare predator numbers across the years to identify correlations between other external factors such as weather events and mast seasons, to explain ebbs and flows in predator abundances.
Where do we monitor?
Our monitoring line network was set up in 2017 by Auckland Council’s RIMU department with robust, stratified random sampling to select a variety of reserves and lines.
The map below demonstrates where these monitoring lines are across Kaipātiki.
These are the sites of the chew card lines. The red markers were surveyed in 2026. The black markers were not surveyed this year because the reserve is closed due to Kauri dieback, or the line is inaccessible due to storm damage to the tracks.
What results do we take from the chew cards? Relative Abundance Indexes (RAI)
Each year the target set for us by Auckland Council is to get an RAI (relative abundance index) of less than 10%. This number is taken from the percentage of cards chewed out of any one line. For example, if 7/10 cards have rat chews on them, then that is 70% Rat RAI for that line.
Eg: 7 Cards out of 10 have Rat chews. 7/10 = 0.7 or 70% RA for Rats for that monitoring line
What did we find from 2026?
This graph depicts which species were detected on each line for 2026
Positive results from 2025 to 2026
This graph shows the monitoring lines that have reduced in Rat RAI to below the 10% Auckland Council threshold from 2025 to 2026 .
This graph shows the monitoring lines that have reduced in Possum RAI to below the 10% Auckland Council threshold from 2025 to 2026.
The rat and possum monitoring results for these lines paint a great picture of what can happen under volunteer control to reduce the number of pests detected. For possum numbers especially, Onepoto domain is a great example. The expert possum remover - our volunteer Duncan, was able to remove 24 possums in the time span of 5 months. That has shown in the results with no possum sign detected this year in Onepoto Domain.
What did we find from 2026? Monitoring lines with abundances higher than 10% in 2026
This graph shows the monitoring lines that have rat RAI above the 10% Auckland Council threshold in 2026
This graph shows the monitoring lines that have Possum RAI above the 10% Auckland Council threshold in 2026
27/68 of the lines we monitored had a Rat RAI above the council 10% threshold.
60% of our lines are within the Auckland Council Threshold for rats!
What we can observe from these results is that there are some areas in which we really need to target our predator control. For the 40% that aren't within the threshold, we need to work on increasing our predator control efforts in those areas. Of those 27 lines, 8 of them have no current predator control in them. For the ones with predator control, we need to look at refreshing the way we do predator control and reaching out to any new volunteers who may be able to help!
For possum control, we are already working to target those areas which have shown high RA for possums. We are establishing a line in Smiths Bush Reserve, looking to install automatic traps in Arcadia Reserve and reaching out to Takapuna Golf Course to see how we can support their trapping efforts.
Moho Perurū (Banded Rail) and Pūweto (Spotless Crake) as examples of ecosystem success
Potential change in monitoring methods for PFK
We are looking to get volunteer feedback on switching from chew cards to a combination of wax tags and tracking tunnels. This will likely begin in 2028 as it will be a big task to set it up and we need to confirm eligibility with funding. This move is going to take some effort to set up initially - both by volunteers and staff.
We want to move to this method as an organization primarily as it is the standard monitoring method across Auckland Council, and across most environmental groups in Aotearoa. It has the potential to uncover other species not detected or obstructed with chew cards. Tracking tunnels can provide data on invertebrates and lizards as well as other species - a way for us to find out the positive of what's in our reserves, not just the negative!
By next year we will have ten years of data from the chew cards - a great feat! For us however, this switch will put us in a position to be able to compare results with other projects, while still having our ten-year data set as an amazing tool for showcasing what has been done historically.
We will circulate a survey to get feedback on this change in the coming months and would appreciate your feedback!
Ngā mihi nui once again, we would not be able to do any of this work without the volunteers. Please sign up for the chew card campaign in 2027 so we can continue this great work! 😊
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