Below are a few observations from our experiments with live capture traps. As noted in our previous blog post, they seem to work better than other traps we have tried. We know they are not the long-term solution, but we need some devices that are more guaranteed to take out predators while we trial different audio lures. We don't want predators to learn and ignore audio lures that we test.
Below is a video showing a few interesting things about the live capture. We explain these in more detail below.
Video 1: Issues and opportunities with live capture traps
In the video, there are two types of live capture traps. The longer one is open at both ends with a food lure in the middle. The theory behind this is that it looks very open and non-threatening, and is not barrier for predators to walk through. This is the trap that previous experiments showed working significantly better than Good Nature and Timms traps.
The second type of live capture trap is shorter, with a mirror on the back surface. In these videos there is no food bait in the short trap, but food in the longer trap.
The surprising first observation is that the shorter mirror trap seems to work better than the food baited trap for possums. Maybe it was just a fluke, but the first time we put the small trap out we caught a possum. The previous week we had seen lots of possums just walking past the other trap.
The very next night we saw another possum come to the same trap, again reinforcing the idea of scent lure trails to a particular place. For the second possum, clearly it was just too big to get caught! Putting the trigger plate a bit further in the trap would obviously help the design of this trap. Interestingly, a possum revisited the trap a few times later that same evening which indicated it didn't seem scared off by the experience of nearly being trapped. We are assuming it is the same possum, but don't know for sure.
A couple of nights later the same possum or one of similar size was caught in a small trap as well. The other interesting thing about this is how the trap door only just caught enough of the possum to suspend it, and as it wriggled, the trap door finally went all the way down. It is encouraging that possums don't seem too bright when it comes to learning about traps.
We tried to test if it was the mirror that was the alluring thing for possums. We put two mirrors in the middle of longer trap. This allows it to lure from both directions and the trigger plate is far enough in to make sure they are trapped. However, we have yet to catch anything using this set up.
The following weeks we have not caught any other possums, despite them being visibly present on camera. Their normal behaviour involves just walking past.
The other part of the video shows the issue with non-target species being caught. In this case a black bird. When we have the artificial intelligence working we could use this to activate the trap rather than rely on a mechanical trip plate. This would also help with large possums escaping from the smaller cage.
In the long-term, the aim of our device will be to track the predators, identify them 100% and most likely squirt them with poison. In the mid-term, we may create a more flexible cage trap that has a higher catch rate that will enable us to do more robust testing of the sound lures. We also need the device to be able to capture more than just one type of predator, which is why we are not using equipment like leg hold traps.
As with our philosophy of open source, we don't put these results up as scientifically significant. They are just a discussion of what we are observing along the way, with the hope that others may be able to chip in and help work things out faster.
We’re always happy to hear your feedback, so please contact us if you would like to discuss anything.