A Better Expansion Collar

The Problem

Tracking animals has a myriad of benefits including gaining a better understanding of habit and space use, survival and responses to management and conservation efforts. Young animals usually make up the bulk of populations, but tracking them using collars usually means either limiting studies to short periods, or relying on fairly crude methods for collars to expand, because young animals eventually outgrow collars. In turn, this means such animals either have to be ignored in the future, or recaptured to continue study, which has potentially undesirable impacts on the animals, and the bottom lines of researchers attempting to study them.

Our Proposal

I propose exploring some novel approaches to building expandable collars, utilising a design used in a prototype drop-off system originally built for koala tracking collars. A rudimentary "proof-of-concept" (PoC) device has already been built, which consists of a series of momentary switches placed around the inside of a collar that would be worn by an animal. The principle is that, if all the switches are simultaneously depressed, a circuit is completed that activates an expandable section of the collar. This initial PoC device was successfully demonstrated using a balloon to mimic the growing of an animal to the point that the switches were depressed and the collar expanded (see attached). This design, along with more sophisticated versions that utilises other sensor data (e.g. "pressure sensors") interpreted by a microcontroller to produce a two-stage collar (i.e. initial expansion and then a final drop-off) are proposed, all of which shall be released through an open-source journal.

We Assume that...

Constraints to Overcome

Expansion collars and drop-off devices more generally don't seem to have progressed much in recent years. Reasons might include a relatively small market for wildlife tracking devices, or some inherent unreliability in designs leading to avoidance of use. Our drop-off design is radically simple and to-date, has never failed. Instead of relying on a complicated sequence of events or moving parts, our design uses nichrome and nylon fishing line (at various gauges depending on breaking strain requirements) to achieve detachment. The same principle will be applied to the expansion collar.

Current Work

Build two distinct prototype devices (as previously described: "dumb" and "smarter") that can be independently replicated, improved upon and tested via open-sourcing.

Current Needs

Funding will be used to purchase materials such as electronic and waterproofing components to supplement existing materials that can be provided in-kind (e.g. leatherite collar material). Some funds will be used to cover the time to document prototype development for open-source release.