subject: Wildlife Tracking Technologies - Which Is Right for Your Project [print this page] Wildlife Tracking Technologies - Which Is Right for Your Project
This is a very short listing of some of those technologies and how they are useful in wildlife research.
The most prolific tracking equipment in wildlife studies is VHF transmitters. They have been around since the 1960s. Wildlife biologists continue to use them today. They work by tracking the VHF signal with a VHF receiver and directional antenna. These are labor intensive devices that are most often tracked manually. The flip side to their labor intensive nature is that they are inexpensive so if you have a lot of cheap labor and very little money they are the obvious choice. There are over 25 different VHF transmitter manufactures around the world. They exist in The USA, Canada, Mexico, Sweden, Germany, The U.K., New Zealand, Australia and South Africa.
Another common technology is P.I.T. tags. P.I.T. stands for passive integrated transponder. These utilize a tiny transponder and are most often used for fish studies. Because the P.I.T. tag has no power source and derives its power from the device that registers or reads it, the tag has to pass through a field containing the power. The field is created by the reader coupled with an antenna and has very short range. For fish traveling either upstream or downstream they are perfect as one can set up the antenna system either on shore or over the river and when the fish pass by a data logger can record that event. These probably have little usefulness on terrestrial animal projects.
Moving on to a more high tech device we come to the PTT tags. These are satellite transmitters that utilize an old and small satellite communication system called ARGOS. ARGOS has been around since the 1970s. While the transmitters have gotten smaller the number of satellites in orbit remains small and that means that the user has only certain windows of opportunity in which data can be sent from the transmitter to the satellite. These PTT tags, in their rawest form, are merely satellite transmitters. However a hybrid system has developed that utilizes the ARGOS system to relay GPS position data stored in a collar. Please don't confuse ARGOS with GPS, the only thing they have in common is that they both utilize satellites, the similarities end there. ARGOS tends to be a rather expensive system to use in that one has monthly subscription fees to pay while the study is ongoing. ARGOS satellite transmitters emit signals that are eventually used to triangulate a position. The triangulation is the result of a signal sent from the transmitter on earth up to satellites in the sky. The precision of these triangulations leaves something to be desired. ARGOS is now mostly used to deliver GPS data from a device to the end user rather than being the key to the animal location itself. Said another way, the ARGOS platform has been surpassed by GPS in regard to positioning although it is still useful as a method by with GPS data can be transmitted to the end user's email account.
Another system is GPS. Everyone knows what this is right? GPS is a global satellite system that transmits signals down to the earth all the time. There are usually over 20 operational GPS satellites in orbit at any given time. Each satellite contains two atomic clocks so that there is a precise time stamp on every signal sent from the satellite. As the position of the satellite in space is known, the time the signal is sent is known and the speed at which that signal travels is known, a GPS receiver can calculate position by triangulation of the signals received from the satellites. Signals from at least 3 satellites must be received in order for the GPS receiver to generate a position. The GPS receiver is the device that the animal carries. GPS has been around since the 1970s too but it wasn't until the 1980s that it because a platform available for commercial use. There are no subscription fees associated with the GPS satellite system, it comes to the world for free through the generosity of Uncle Sam. But how the GPS data is transmitted from the device on the study animal to you, the user, is a matter for another article. If your project is well funded you will find that GPS products offer you the most latitude to configure a product that is specifically geared for your project.
GPS does not work under water so if your project is in a marine environment most GPS devices won't work although there are a few that employ a technology that will post process information gathered by the GPS receiver when the receiver's antenna is out of the water. The problem with this is that the device must be recovered in order to extract that information and post process it to gain the resultant GPS positions.
Quintin Kermeen
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