Making Predator Fences Active
Once an area has been cleared of predators, how can we defend it? The traditional answer has been static fences. Today we introduce a new concept - making those fences active.
Before we introduce our new design, let's take a moment to have a quick review of fences and the terms used to describe them.
Permanent predator fences:- large, expensive, physical fences used around predator free areas (and typically cost between $400-500 per metre). Potentially block as much as 99% of all predators, in a few cases perhaps even 100% until something goes wrong (maintenance failure, bank of snow providing a ramp, tree falls on fence etc.)
Leaky predator fences:- less expensive typically smaller fences that block some predators but not all. Some would argue that all fences have some form of leakage but leaky fences are more explicit about the compromise between cost and effectiveness. These fences accept that some animals will make their way over or through the fence.
Virtual predator fences:- no actual barrier other than lots of devices for capturing predators. The most comprehensive example of these are being trialed by ZIP.org.nz. To date these have been shown to let more predators through than the two options above
And now:
Active predator fences:- this is a new type of fence that is designed to actively catch predators that interact with it and it is also movable (hence active). It uses inexpensive movable "hazing" style fencing to guide predators into traps. The fence can be deployed in multiple lines and can be moved to sweep through an area to make it predator free. Using lightweight, movable fence lines as an eradication method is a new concept - see the video below for some early encouraging results. Active fences may prove to be a very low cost way to protect predator free areas.
Here at The Cacophony Project, we've been through several iterations of portable fence design and tested them in a number of settings. Below is a video that shows a few different fence set ups and how each seems to be quite successful at guiding predators through (designed) gaps in the fence. We have tested this for several months and seen hundreds of predator interactions. So far we have only seen a couple of predators climb the fence and that was only after they had already been through a gap in the fence previously. We suspect that once a predator is familiar with what is on the other side, it is happy to climb over. But the really encouraging result is that the first instinct of all predators appears to be to wander along the fence and go through a gap (where, in a full deployment, they will encounter an open architecture trap).
Our goal is to put our open architecture traps in these gaps and show that a relatively inexpensive fence linked with high interaction traps can be an effective predator barrier. This is a key addition to the tool kit in the pursuit of 100% predator free areas.
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.
