It’s been a busy summer with lots of news to share – we’ve completed last year’s baiting round, reached the milestone of over 2000 rat catches recorded since 2015, and have been safely working throughout the Red restrictions to protect the taonga species that call the Ark home.
The Ark team started pest control in 2002, with data entry moving to CatchIT in 2015. From a start of 150 traps checked and five catches in September 2015, our incredible trappers checked 1596 traps in January 2022 removing 90 pests!
Thank you trappers!!
The trapping team have been busy throughout the summer break and January saw an almost record number of catches – 90 this year, compared to the peak of 96 in January 2020.
February this year saw similar results, with a second highest record of 53 catches compared to the peak of 61 in February of 2020.
The high trapping numbers have been made up of a mixture of pests, you can explore the breakdowns more here, including a map showing hotspots for each pest species. During these last four summer months (Nov-Feb) trappers removed 129 rats, 72 stoats, and 20 possums. Stoats are a huge problem for our native species as they are voracious hunters – Te Korowai o Waiheke have some fantastic information about their impacts.
Tips for getting the best results from your traps:
- Trapping master and Volunteer Representative Ken shows us how to weight test your DOC200
- Every pest has a different personality, much like our pets. Not every pest will love peanut butter, move through an area in the same way, or interact with every type of trap
- Creating a ‘play gym’ around a trap helped the Shakespeare team eliminate the stoats that infiltrated their fence
- Get creative with baits and camouflage, without changing the humaneness of the trap or encouraging non-target catches
- Send us photos and stories to let us know what works and doesn’t work, to help us all trap better!
- Read up to learn more about how each species behaves, like this amazing resource suggesting trying chocolate for attracting rats into your traps
- Note from Sam: I had pet rats for a number of years, and can confirm their favourite snack was Squiggles chocolate biscuits!
Trap catch update
The summer heat map is ready to delve into. As you can see it’s been a busy summer for our trappers – 6107 traps checked removing 281 pests, compared to 5773 checks removing 174 pests the previous summer. Why the difference?
The stats:
- 83 rats in 2020/21, and 129 this summer
- 39 mustelids (stoats, ferrets, & weasels) in 2020/21, and 76 this summer
- 24 possums in 2020/21, and 20 this summer
- 18 hedgehogs in 2020/21, and 37 this summer
So possum numbers are the only catch rate similar to last summer (decrease of 17%), with other groups increasing by 55% (rats), 95% (mustelids), and 106% (hedgehogs). This data helps us review our trapping plans: in areas where there are still infrequently pests when trap visits are undertaken, we know we’re checking traps as often, or more frequently than is needed.
Hotspots will be reviewed – if we’re catching a lot of one pest in an area, do we need more traps specifically targeting them there? If one area is particularly pest-y, can we increase trap numbers, check more traps, or get more neighbours on board to slow them down before they reach the Ark? If you’re a volunteer or neighbour keep an eye on emails – we may be calling you to ask for help to get these numbers lower.
Pest Monitoring March 2022
Monitoring results are in, and they’re lower than the last round.
With 17.2% tracking of rats within the Ark and 40% outside (Wainamu at present), it’s clear our pest control work is having a positive impact on rat numbers.
The distribution of pests varies across the Ark, with some monitoring lines being visited by far more pests than others. We use this data to focus pest control – while monitoring results show plenty of rat activity at the eastern end of the Cutty Grass monitoring line, the nearest traplines (Rata Access and Cutty Grass South) don’t show high trapping numbers.
We’ll look into this further when we analyse bait uptake data: do we need to re-think lures along those trap lines if rats are in the general area but evading traps, or are the rats exclusively living around the monitoring line and the nearby waterway without populations spreading and reaching the traplines?
(Right click and ‘open image in new tab’ to see bigger version of the map).
The amazing work undertaken by the Ark team since the beginning of the project in 2002 means we can compare rat monitoring rates now to those from the beginning of the Ark.
There are some things that make comparisons tricky. The Ark has grown in size over time so monitoring data first collected over 250ha is now collected over 2200ha. Also, the ‘outside’ monitoring line which gives us an indication of what local pests are doing in neighbouring uncontrolled areas has changed, after the area that was once used began to receive pest control. Limits like lockdowns also impact our analyses, as we were only able to complete one full pest monitor in 2020. Time of year has a strong impact on pest populations as well as their likelihood to interact with pest monitoring tunnels.
While control was very effective at the beginning of the project, shown by the rat tracking percentage being consistently low from early 2005 to late 2013, pest populations constantly adapt. It is likely other factors like climate change are also impacting the effectiveness of control methods as well as pest population growth, with heavy fruiting years resulting in higher pest numbers with the extra food available in the ecosystem. We’re currently reviewing our pest control methods and tools, and will have updates in our 5 year plan due out late 2022/early 2023.
Coming in the next update:
Summary of the mustelid scent trial that took place with Patrick Garvey from Manaaki Whenua. Did the scent lure trial undertaken by our trappers contribute to the high number of catches this summer?
