The previous blog posts showed how a simple model can help understand typical predator elimination methods. It makes intuitive sense that long life lure or automatic dispensing lures will help with trapping. In this blog we discuss the impact of automatic lures and long life lures for their potential to achieve total predator elimination.
Automatic lure dispensers and long life lures
A number of organisations are working on automatic lure dispensers and long life lures and it makes a lot of sense in terms of labour saving but we want to understand just how much difference they will make when it comes to total elimination of predators.
Referring to the graph below, the red line shows the predator population trend for an automatically lured trap. The blue line shows the case of traps re-baited manually every two months. If the trap is not re-baited (orange line), the model assumes the trap will become ineffective. The more often traps are re-baited the more often they are likely to attract predators. The model clearly shows that a full automatic lure dispenser is an improvement but still doesn’t make a massive difference to the overall predator population compared to regularly re-baited traps.
Once again, the reason automated lure dispensing doesn’t make much difference is that a very large proportion of predators just walk on by existing fresh food based lures. The video below shows 6 traps with different freshly baited lures.
Making the lures long life or automatically re-baiting doesn't make much difference if predators don’t interact with freshly baited traps. However, if there was a trap with a very high interaction rate it could certainly be useful to have automated lures. Automatic and long life lures do help reduce labour costs if you are interested in predator suppression but our goal is total elimination hence they seem to be of limited value.
Note: See here for the good work our friends at ZIP have done showing lure dispensers can help with research and monitoring too: https://zip.org.nz/findings/2019/12/the-many-applications-of-the-zip-motolure
Our goal here is not to be negative about a large range of intuitively useful things but to explicitly state what our data is showing. Slight improvements to devices most predators walk past have very little impact on total predator elimination. There are lots of ways to improve predator interaction rates that we will highlight in a following blog. We don’t think we have all the answers but are keen to make it more widely known what an issue the interaction rate is so that more people are focused on that rather than things less likely to make a difference.
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