The I-gotU GPS logger was originally marketed to track the movements of pets and kids by attaching to a collar or strap, and was advertized by some for tracking spouses or teens by hiding them in a car. They really need a clear view of the sky to get good position fixes. Identical loggers were sold under different names, and use the same software for configuration and reading.
They are being phased out, but are still available on Ebay or new at other sources. Usual cost is about $30, and software is free.
The I-gotU GT-120 loggers (and their twins) have capabilities out-of-the-box that make them suitable for some Box turtle tracking activities for some users. Despite the toy-ish appearance, the plastic case is pretty tough, at least until they get chewed on by animals, or degraded by UV sunlight. They are not water-PROOF but when covered with plastic mailing tape they can be water-proofed, at least until the tape gets torn or drys in the sun.
From a fully charged battery, they can be configured to record at least 30 to 60 days (or more), when recording at an interval of 1 location per hour, and by dissabling all LED indicator lights. They can be scheduled to start recording at a future date, and to record locations only during preferred days, and/or hours.
Using radio telemetry to locate, and a GPS to record the locations of a Box turtle, only gives a rough indication of the actual route traveled, and no information about activity hours. The more frequent the tracking, the better approximation of the turtle's travels. The graphic interpretation found here demonstates the magnitude of error possible when telelmetry tracking is limited.
Thread trailing records, on the ground, the true movements of a Box turtle, but is very labour intensive, and requires sketching or following the thread with a handheld GPS to record the travel information onto maps.
A GPS logger is a GPS receiver that records it's position to memory for later retrieval. They do not have the capability to transmit data to a satellite or cell phone, but consequently, are much less expensive, smaller, lighter, and draw much less battery power. For recording the movements of an animal the size of an Eastern Box turtle, the GPS logger is more than adequet. Automatic GPS logging needs to be thought of as a supplement to telemetry which has benefits of observing turtle meetings and matings, finding new population members, transients, etc.
Below are the currently available and affordable GPS logger options suitable for use in Box turtle research. Each is much lower cost than a telemetry transmitter, but must be used in conjuction with telemetry so the logger can be retreived and the data off-loaded.
The Catlog Control Center software is where the GPS logger is configured before being launched, and the GPS location information in logger memory is read after being retreived.
For use with Box turtle research, a logger can be configured to record only at specified hours of the day, at specified time intervals, and with or without the LED showing logging activity
For example, log only between daybreak and 2 p.m., only 1 location per hour, and disable all LED indicator lights.
The battery simulator gives an approximation of the recording time for a given battery size.
For use with Box turtles, a recording interval of 1 hour between GPS fixes, using a 450mah battery, gives about 42 days of recording, or 95 days when the LED indicator lights are disabled.
The Catlog Gen 2 price is $58 USD including thermoseal heat shrink and battery. The bare PC board version without battery or enclosure, is $49 USD each.
The Gen 2 GPS loggers are completely customizable when ordering. Battery size, enclosure type, communications connector (among other things) are supplied to order. Mr.Lee doesn't put out a price sheet, but will supply a price based on the user's desires. The software is free.
These photos are of the Catlog Gen 2 bare board, without battery or enclosure, but does include the USB connector. The board size is approximately 20mm x 27mm x 8mm. The liPo battery that would be the right size to sit directly under the the module is a 402030 that would add 4.3 grams for a 200mah version.
One option is this clear epoxy enclosure. The epoxy encases everything including the battery, and makes the logger weather-proof, and probably rodent and predator proof.
The potted version is heavier than other options, but for use with Box turtles, size (and shape) is more important than weight. This type of potting is done by many as a hobby/craft and could be used as a method to form a dovetail or other type of connector integral into the bottom of the enclosure.
The little glass tube on the top of the module is a magnetic reed switch which is used in place of a mechanical switch to activate and turn off the logging activity. It's similar to, but not identical to, the magnetic reed switch on most telemetry transmitters. This GPS logger can be configured, via software, to start logging at a specified date and time, so the magnetic switch is superfluous to it's operation, if desired.
This incredibly tiny GPS logger is small enough to be attached to any Box turtle large enough to be carrying a telemetry transmitter, and cost about 1/3 to 1/4th the price of a commercially available transmitter.
The bare board (no battery or enclosure) is only 5.8 grams and 20x27x8 mm. The battery adds a few grams (4.6g for 200mah), and the enclosure a few more grams. For greater recording times a 450mah 702030 battery adds 7mm to the thickness dimension of the unit, or a 500mah 902030 adds 9mm.
The logger, as sold, is 28x45x13 mm, 21.6 grams, and contains a 380mah rechargable battery. Replacing the standard battery with a 600mah version (a snug fit) adds only 3.5 grams and at least another month of recording.
This logger is probably around the maximum size that should be attached to an adult Box turtle (along with a telemetry transmitter), and not seriously impede movement or effect behaviour. The weight is fine, and even the shape is good for movement through brush, grass, etc.
Youtube has a number of instructional movies about this logger. Here's a user's manual and software instructions.
The internal indicator LED's evidently consume a lot of power. By disabling them (via software) the logging time can be almost doubled.
The single big button is used to start and stop logging, but can be disabled via software.
This is the Canmore GT-740FL GPS Data Logger. It has a USB rechargable battery and only 2 buttons. It is configurable using software and is, as far as I can tell, water resistant by way of a sealed housing and rubber O-ring.
This GPS is advertized as the "SportsBook", geared toward joggers and runners, but is evidently sensitive enough (SiRF Chipset), that it is also promoted as a tracking device that can be put in a car's glove compartment or in a briefcase and still work.
I use this GPS to record my own travels as I track my study turtles. It is configured to record a position every 3 seconds, and I usually download the route data every week or so. It works well inside the front pocket of my pack, and costs about $40.00 new on Ebay.
This GPS is small enough and light enough to be attached to an adult Box turtle to record daily travels, although the shape of the case is not ideal. The greatest feature that makes this GPS good for turtle tracking is that it has an internal motion detector which puts the recorder in "sleep" mode after it has not moved for 5 minutes. The small rechargable battery should power the logger a very long time before having to be re-charged, due to the amount of time a Box turtle stays in a form each day.
The Photomate 887 is one of the smallest ( ) and lightest ( ) GPS loggers around, but may not be found for sale anywhere anymore. It appears that there never were many available, but that may be because, despite the small size and good performance, it was supplied with the very worse software ever provided with a commercial GPS product. But once again, GPSBabel (free) comes to the rescue, at least for downloading logged points and routes.
This unit has an internal battery charged via the mini-USB port, and only one button serving several functions. There are 2 versions, one with Bluetooth, and one without. With aftermarket software it can be read through a Bluetooth connection, but for use on Box turtles, because of it's limited battery time, the logger needs to be removed for charging often anyway, so it can simply be read at that time.
The case is thin plastic, and is not "potted", so is likely not water resistant unless sealed with silicone or epoxy. The USB port needs to be plugged for field use, and the button sealed somehow.
It's advertized to have something called "Auto On-Off" as well as "Smart Power", but neither is explained or even mentioned in the user documentation.
Photomate 887 GPS Logger
Home-Made GPS Logger (project)
For about $18 and a minor amount of soldering, a reliable GPS logger can be assembled that is able to record up to 100,000 points and is small enough and light enough to be attached to an adult Box turtle in a similar manner as a telemetry transmitter. The manufacture probably made a million of these "3 in 1" GPS logger USB dongles and they were sold under a number of different brand names. They were not very popular, so now they sell on EBAY very cheaply.
Out of the box, these loggers start recording as soon as they are plugged into a USB or other power source. When connected to a computer, the included simple software can configure the logger for recording choices, and download and export the track logs (waypoints) in standard formats. The dongle has no internal battery, so it stops logging as soon as it is disconnected from a power source.
By simply adding a battery, between 3.6 and 8 volts, a complete, portable GPS logger can be assembled. But Eastern Box turtles rarely move at night, and most don't travel after about 2:00 p.m., so there is really little need to be filling the memory with points and using battery power during those times of the day.
Configuring the logger to record a point every 5 minutes or so, would reduce the number of unnecessary points being recorded, but the logger will still be using battery power when not logging. Adding a timer that would turn the logger on only during early morning hours would save power and the number of recorded points. That might also miss recording important movements.
Instead of using a clock/timer, a motion detector and delay timer would turn on power whenever the turtle moved, and continue recording for (say) 5 minutes before turning off. If the turtle moved during this delay time, the power would remain on and the recording would continue until 5 minutes after the turtle stopped moving. The logger draws only about 15 milliamps when recording.
The parts needed to build a logging GPS are delay timers (only one is used), and "3-in-1" USB GPS logger dongle. A Lithium battery is used for power, although a solar cell and rechargable battery would also work.
The timer module is epoxied to the empty flat space on the GPS beside the antenna.
The photo shows the GPS removed from it's plastic case. There are no loose wires to worry about. At to bottom of the GPS is the USB connector which will be removed and replaced with a smaller version to make the completed logger shorter and smaller. The silver square item at the top is the GPS antenna which must always point out.