Goals of an Electronic Tagging System:
As with any game tagging scheme, the primary goal of our tracking tags are to monitor the movement of selected species within the Galapagos. Our intent is to do this with as little intrusion as possible into the animal's habitat. The species that we chose are all either on the endangered or on the "keystone" species list and are non-avian, a complete listing of which can be found in the Appendix. We established these parameters because there are a plethora of species present on the islands. Of these species, however, there are only a select few that drastically impact the rest of the ecosystem or are in danger of leaving the ecosystem altogether and generating repercussions that cannot yet be fathomed. In attempting to protect these two classifications of species we believe that we will see the largest proportion of applicable data results to resources expended and environmental impact.
Our mission of monitoring animal movement while still minimizing human interaction generates quite a problem as tags do not manifest themselves on the subject wished to be studied. Human impact can be minimized, however, in observation of these tags. It is due to this consideration that we decided traditional tagging of animals was an unacceptable solution. A synergy of modern technology and traditional techniques provides the optimal solution to this perplexing problem.
We believe that the contemporary use of technology and traditional tagging techniques with an innovative spin on design will assure results more complete and have less environmental impact than any previous system of similar size and scope. Implementation of these three ideas as a single unit is simple conceptually, but actually mass producing a field worth design that works like it should a vast majority of the time is no small task. For the scope of this project we are dealing primarily in hypotheticals, although we have attempted to keep a realistic perspective throughout our sensor designs, this is by far the most radical and experimental. We believe, however, that at the current rate of advancement in the fields of nanotechnology, electrical engineering of batteries, and wireless communications that a feasible solution could be developed to at least the prototype level on the order of two to three years with a fully deployable system in place within five years.
The electronic tag was conceived around the notion of a hospital patient tag, the kind that is worn around the wrist as a watch. This causes less physical damage to the animal than a traditional piercing tag and allows placement on any animal that has appendages without worry of the wound healing or an ensuing infection. The band is designed with an adjustable fastening system to ensure a firm, but not constricting fit around the animal's leg. The width of the band would be approximately 2 cm while we hope to keep the thickness to under 50 mm, but that is more subject to technical specification that must be determined through experimentation, to allow the wristband to be standardized and used across the maximum number of species with minimal intrusion.
Material selection for the tag is critical if a tag is to remain in place for more than a few hours. Animals are certain to attempt to remove it, it will be subjected to the elements, and the general wear and tear are all factors that will adversely affect the lifespan of such sensors. Thus the tear and sheer strength as well as the abrasion and corrosion resistance of the material are paramount no to mention the protection of some relatively fragile electronics. Thus with these considerations as well as the comfort of the animal in mind we believe that a lamination of thin films between a shell of kevlar or similar material that is amazingly strong yet lightweight with the qualities that we listed above. This should encapsulate a layer of silicon that will protect the electronic components from moisture. Within this layer a small, high gain antennae of some good conductor will be coiled around the band to ensure a range on the order of 2.5 km or better to allow the reception nodes to allow for triangulation of animal positions or at least regional identification (Outmesguine, 2004). Within this layer a sandwich of the heart and power plant of he system should be constructed one atop the other. An implementation of the ZigBee technology, initiative 802.15.4 of the IEEE, upon a thin film, most likely a flexible plastic, atop a thin film lithium ion battery. This layering technique provides for both amazing portability and longevity as we hope to maintain between 2-3 years of service from each tag before replacement is necessary (Zigbee Alliance, 2004).
In the event that our materials choices or design are flawed on in some way or newet, better technology become available, a revision is a necessity, but immediate changes would be a logistic and statistic nightmare. We suggest a biannual revision of the design to there will be ample time to redress each suggested revision between the times of placement every other year. Not only does this assure that our tags our current with the present technology, but that we are receiving the best possible information per sensor possible at that time.
These tags are an integral part of the system but provide very little actual data if they have no way to communicate it to the scientific community. The communication infrastructure of ZigBee that we selected was chosen for its small size, low power consumption rate, future expandability, and its range when combined with the proper antennae, all of which are vital for miniaturization of the sensor. While the tagging sensor is smaller, the frequency upon which it works is different than the one used by the communication standard of the sensor nodes. Due to the relatively even spacing of the sensor nodes, however, it makes sense to place the ZigBee receiver at each sensor nodes so that all of our equipment is at one easily accessible location and so we can tap into the information backbone of the ARGOS satellite system without the need to implement another obstruction into the environment. The concept of combining both the sensor nodes and the electronic tagging system into one unit greatly, but not entirely, motivated the decision to space the sensor nodes approximately 5 km apart due to the limited communications range, based upon the size of the transmitter, of the ZigBee system. Then utilizing the same communications strategy as described in Sensor Node Transmission Handling and the algorithm described in Algorithm Design and Data Handling we have a nicely integrated system that provides much information without much additional hardware (Zigbee Alliance, 2004).
Unfortunately the most intrusive part of game tagging is the tagging procedure itself. It requires direct human interaction with the animal to be studied. We believe the only feasible solution to sensor attachment are the traditional techniques of human interaction in attaching the sensor to the animal subjects. Several small teams of 3-5 scientists operating on foot out of backpacks could be placed on each of the larger islands and one each on the smaller islands at the conclusion of the spring mating so as not to interrupt this most important period of the year. They will most likely not need to use tranquilizers on the reptiles on the list because many are so lethargic or slow moving that the scientists can easily capture and attach tags to them. The mammals on the list may require the use of a tranquilizer such as phencyclidine, but these are widely accepted across the world as an acceptable means of incapacitating animals without killing them.
The scientists will carry an assortment of tag sizes so that there is no excessive tightness or looseness experienced by the animals in wearing the tags. This is to prevent the tag from being caught on brush or other obstruction that may impede upon the survival skills of the animal or from restricting blood flow to the appendage. While it is true that the tags placed on smaller animals will have lesser transmittance distance and may provide slightly less accurate data we believe that it is more important that the data collected is vailible for partial analysis rather than have no data altogether.
For a period of two weeks they could place the tags on the species listed in the appendix. Further during this interval these teams will check the status and provide basic maintenance on the sensor nodes and evaluate whether further, more technical repairs are needed.