Trap development update
Our high catch rate trap has now been out in the wild in a few areas so it's time to give you a brief update. We've identified some key next steps in the trap's development.
Some things we've seen so far:
The trap has now consistently caught a wide range of predator types; ferrets, weasels, stoats, rats, possums, hedgehogs, and feral cats.
Some encouraging results in one spot where one trap caught 16 possums in 6 weeks. Following that, no possums were seen in that area for the following 5 weeks. This type of result gives us confidence that the trap will be a useful tool in trapping areas to zero.
We have seen a higher catch rate than any other device we have tested: Of the encounters seen by our cameras, our trap has successfully caught 10-60% (it varies by species, the larger the species, the better the catch rate with this version of the trap). That catch rate compares favourably to the 1-10% rate we see for other devices. We need to collect a lot more data before we will have statistically significant data to confirm this.
We have developed the first version of an auto-reset mechanism so that we can do multi-catches linked to multiple live capture traps.
The key unknowns around animal behaviour look very positive in that animals are happy to go into the open space, that the blinds are fast enough to trap the predators, and that they all go straight into the cage (rather than trying to get through the blinds).
The use of our low height, portable, active fence in conjunction with the high interaction rate trap has shown a significant increase in guiding the animal through the capture area.
We have simplified the trap layout to only have 2 blinds (as opposed to 3). Combined with the portable hazing fence this gives us a simpler, more robust set up.
Below is a thermal video of a wild stoat being caught in the Otago bush.
The work on the trap continues - here are some of the next set of things we are working on:
Making a lower cost, more robust version of the trap
Taking weight out of the trap and improving usability. One project that looks promising will take 95% of the weight out of the auto reset and trigger mechanisms. You may ask why we didn’t just design it light first time but there is no point trying to make something light until you know if it is going to work in principle.
Improving the trap trigger. We have seen a few instances of the current trigger not working reliably for small rats or mice. Also, for larger predators, we have seen a few instances of it triggering before the animal is fully inside the capture area (our current trigger uses a crude motion sensor).
The next part of the project will use a high resolution camera that has an artificial intelligent trigger. This is a significant piece of work that will enable the trap to safely allow non-target animals to pass through the capture area without triggering. Once we have an intelligent trigger that avoids by-catch, this will allow us to introduce an automated killing mechanism. The combination of these components will dramatically reduce the cost and effort of servicing the traps as they will no longer need to be monitored each day (which is the case while the trap remains a live capture device).
Improve the cage door trigger mechanism. The current version of the trap uses an off the shelf live capture cage which is fine for everything apart from rats (though seems to work fine for larger rats). We need a more sensitive door trigger for them and a cage with smaller mesh. We have tested a 12x12mm mesh covered auto door cage that has caught and retained a mouse. We have tested an automatic, self latching and resetting cage door.
Developing an auto killing mechanism. For this part of the project we are looking to also trial integration of tools that are being developed by other organisations e.g. spitfire, NZ auto trap, hammer force etc. The first version of this will require a human confirmation step before activating the killing mechanism. This will enable the trap to be left unmonitored in the field. The trap will automatically reset after each kill, which will allow for multiple captures each night.
We continue to test different luring setups for different environments and target predators
If you have a last hard to catch predator we suspect this is the tool with the highest chance of catching it. Catching the last hard to catch predator is much harder than general predator suppression.
We hope you're as excited as we are about these developments - we'll bring you further news as soon as we have it.
As always, we welcome your feedback so don't hesitate to get in touch - leave a comment below or email us at blog@cacophony.org.nz.
