Scientists and researchers specializing in tracking and monitoring the behavioral patterns of wildlife have found telemetry devices to be of great use. One of the most important components of the telemetry system is the tag that is attached to the animal by way of straps, clips or glue or inserted into their bodies with the help of a surgical procedure or some other means. Where the tag will be fixed typically depends upon the type of tag, the sort of animal, and also what is being monitored. The tags themselves come in an assortment of sizes and form factors and are built to be robust enough to be able to withstand the challenging environments encountered in the animal habitat.
Tags That Store Data or Send Data
The basic purpose of affixing a telemetry tag to the animal is to collect information of various types. This could include biorhythms, migration paths, habitat conditions, direction and speed of travel, etc. to name just a few of the dozens of parameters that are typically studied. All tags are built to collect data; some store them, while others transmit it to nearby or remote receivers. The tags that only store data are referred to as archival tags, while the ones that send data are known as transmitting tags. The use of archival tags necessitates the recapture of the animal for information retrieval and since this can be traumatizing to the animal, researchers prefer to use transmitting tags that send information to the receivers, usually by radio frequency signals or sound signals.
However, advancements in technology have made it possible for archival tags to store data pertaining to the behavior of the animal or its habitat of a number of years. The issue of animal recapture and a second surgery to recover implanted tags however remains. The other disadvantage of conventional archival tags is that the data cannot be accessed on a continuous basis and researchers have to wait for extended periods of time before being able to study the information collected and stored in the tags. However, another type of an archival tag is capable of storing data for extended time periods before transmitting it to a satellite.
Satellite Tags
Satellite tags are the only type of telemetry tag that does not require the animal to be recaptured or having to be in a close enough position to receive data from transmitting tags. The use of a satellite tag allows unrestricted freedom to the animal to travel wherever it likes without fear of losing the signal or transmitted data. The monitoring is possible from all places on Earth as the signals are transmitted directly to a satellite after temporary storage in the tag. Data transmission is done by an antenna sending out an electromagnetic pulse that the satellite can receive and forward to a receiving station on land for further decoding and analysis. The antenna however needs to be have unrestricted access to the sky to enable the data to be transmitted. For this system to work, you need to have an agreement with a satellite service provider such as Iridium or ARGOS that have a number of satellites constantly orbiting the Earth. You can learn more about different satellite networks at http://motee.me/.
Pop-Up Archival Tags (PAT)
In order to monitor aquatic animals that spend extended times underwater, pop-up archival tags (PAT) are used. The tags keep on recording and storing the information for a long duration, and when triggered by the program, separates itself from the animal, floats to the water surface and then transmits the data to the designated satellite.
Life History Transmitter (LHX) Tags
Life history transmitting tags or LHX tags are implanted by surgical procedures into the animals to be monitored. The tags keep on recording the data that is accessible only after it comes out of the animal’s body following its death. The tags float to the water surface and transmit the stored data to a satellite, as it is programmed to.
GPS Tags
GPS tags are typically used to monitor the movements of animals. The tags contain global positioning system (GPS) technology that communicates with orbiting satellites to determine the animal’s location and movement. To function properly, they need to be able to communicate with the satellites. The use is thus restricted to only animals that live on the surface of the Earth or aquatic animals that rise frequently to the surface of the water.
VHF Radio Tags
These tags with radio telemetry technology are attached externally to the animal and work by transmitting radio wave pulses to a receiver in close proximity. The closer the animal, louder the beep, so scientists are able to monitor the animal’s movements by measuring the signal strength.
Acoustic Tags
Acoustic tags are typically inserted into aquatic animals living below the surface of the water. The tags produce a pinging sound that is monitored by a hydrophone in the animal’s proximity. The number of animals present near the listening device can be calculated by scientists who can also use the technology to search for a particular animal using movable hydrophones.
Passive Integrated Transponder Tags
This type of tags contains a microchip that has an embedded electronic identification code. The tiny tags are surgically implanted underneath the skin of the animal allowing it to be identified by comparing the code in a computer database. The system obviates the necessity of using physical markers on animals to identify them, however for the tag to be read, the animal must necessarily be in very close proximity to the tag reader.
Author bio: Meryl Jenkins is a senior scientist with extensive experience of monitoring wildlife with the help of electronic tags. A prolific writer on the subject, some of her more recent articles may be read on http://motee.me/.