If you want to be precise and/or accurate you need to test, evaluate results, improve, and test again until you are satisfied with the outcome. This is basically what I have been doing the past two weeks. I had been developing a harness for a microGPS unit which will be attached to tortoises. Concurrently to the radio tracking, the GPS project will also study the Texas tortoises (Gopherus berlandieri) of the Palo Alto Battlefield National Historical Park (PAAL). The radio tracking project gives us a once-a-month snapshot of the activities and location of the tracked tortoises. The microGPS will record 5 locations per day at specific times; 7am, 11am, 1pm, 4pm, and 7pm. This increases the temporal information for the selected tortoise.

I started creating the prototypes using play-doh. After I created the desired shape, I realized that it weighed too much and would not work for our small tortoises. (If you missed my other blog posts, the Texas tortoises are the smallest tortoise species in the United States.) Using aluminum foil as the base and the play-doh to protect the microGPS prongs, the envisioned harness prototype was created. Nevertheless, play-doh and aluminum foil are unfit for the desert environment, so I had to upgrade my materials. Ten models later, using aluminum sheet and epoxy the harness was created.

Harness prototype development

Simultaneously to the development of the harness, we were also testing the accuracy of the GPS. On the first test, we mimicked different environments that the tortoise can be found: open area, under coarse vegetation, and inside of a woodrat midden. Unfortunately our results were very disappointing. After contacting the technical support and changing microGPS settings we got better outcomes. Next week, 2 microGPS units will be deplyed in Brownsville for some field test.

MicroGPS location test

Stay tuned, the next blog post will be about the June field trip to Palo Alto Battlefield National Historical Park.