Biotelemetry: a brief history and future developments in lowering cost

Kevin Xu a , Mark Gartner a a Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA

Kevin Xu

Mark Gartner

Kevin is a junior in the Department of Bioengineering on the cellular engineering track from Mars, PA. Kevin has always had an interest in connecting biomedical concepts to technology and takes pride in helping to find novel approaches to existing problems.

Dr. Gartner is a professor in the Department of Bioengineering, primarily teaching the Senior Design course. After receiving degrees from both Pitt and CMU, Dr. Gartner began his work in medical product design and development at UPMC. Dr. Gartner also co-founded Enison, Inc., a vertically-integrated incubator that developed medical products based on a “surface first” philosophy.

Significance Statement

The study of wildlife behavior is extremely important but is hard to accomplish in its current state due to the lack of accessibility for biotelemetric devices. Through the development and adaptation of current tracking systems, researchers are creating lower-cost devices that will allow for more widespread study of animal species.

Category: Review/perspective paper Keywords: Biotelemetry, wildlife, tracking, history

Abstract

Biotelemetry is crucial to a variety of wildlife and conservation-related assessments. The three main systems used in biotelemetry today (very high frequency transmitters, global positioning system tracking, and satellite tracking) all have advantages and disadvantages, but the expense and difficulty of implementing biotelemetric hardware remains a barrier to entering the field. The recent research and development into newer systems has made it easier to get involved in biotelemetry, yet the cost of hardware still makes it difficult to study many animals in diverse and widespread areas.

Current research into creating lower-cost tracking devices using off-the-shelf, open-source hardware have helped pushed for more access to biotelemetric devices. The continuation of this research and the push for more accessible biotelemetric devices will allow researchers not to only learn more about wildlife behavior, but also factors such as wildlife biology and ecology.

1. Introduction

Wildlife research is a long-standing and extensive field, but the study of animals and wildlife has certainly not been easy. Humans have lived among animals for thousands of years, but for most of this time, information about animals was gathered by simple observation and chance, rather than finding a systematic or quantitative approach to observation. However, with the development of biotelemetry in the 1960s, researchers have been able to improve their study of the general movement and behavior of animals.

Biotelemetry involves the capture and tagging of a species of interest with a transmitter device. Once tagged, the device transmits radio signals to reveal the location of the transmitter and also to relay any other information or data that may be collected. Location data is extremely important and can be used to study an animal’s preferred habitat, home range, and to understand population dynamics. Details into animal movement can reveal fundamental behaviors such as how the animal acquires food, shelter, or mates or how they survive in general.

Typically, biotelemetry involves three different techniques: very high frequency (VHF) transmitters, global positioning system (GPS) tracking, and satellite tracking. VHF tracking is also known as direct tracking and is used in close proximity to the tracker in order to find the exact location of a tagged animal. GPS and satellite tracking allow an animal to be tracked globally and is useful for remote tracking or for tracking migrating animals, since locations can be accurately determined regardless of distance.

While exciting developments are being made in the field of biotelemetry in the improvement of technologies, biotelemetric hardware is extremely expensive and frequently challenging to implement [1]. As a result, only a small number of units are typically purchased and only the most at-risk animals are studied. In addition, the access to these technologies can be extremely difficult in developing countries, and as a result, limitations on sample size must be made in studies [2]. In this paper we will explore (1) the progression and development of new technologies

in the field of biotelemetry and (2) the pursuit of designing and developing low-cost wildlife trackers in order to improve access to studying a larger number of species.

2. Methods

This paper will first aim to explore the development of technologies and techniques in the field of biotelemetry, first starting with the advent of wildlife tracking devices in the use of VHF tracking. The development of very commonly used systems such as GPS tracking and satellite tracking will also be explored, as well as future goals and ambitions for tagging and tracking. This paper will also delve into the development of lowcost wildlife tracking devices, which typically use off-the-shelf hardware that has been modified to serve as a substitute for the more expensive systems currently in use. Many research articles regarding low-cost wildlife tracking devices are written in the study of specific species (e.g. pampas deer, brushtail possum, etc.), but the techniques and goals are applicable to the study of low-cost devices in general. This paper will serve as a general discussion of low-cost tracking devices in the interest of increasing access to studying all animals, not just specific species.

3. Discussion 3.1. History of Wildlife Tracking Devices 3.1.1. VHF Tracking

Figure 1: A park ranger employing VHF tracking to triangulate and track mountain lions.

Very High Frequency (VHF) technology was the first main technique used in biotelemetry to track and identify individual animals. The first successful system was tested in 1963 on rabbits, striped skunks, and raccoons [3]. A VHF tracking system consists of two main components that include the transmitter device used to tag the animal as well as the remote receiver which is usually a hand-held antenna. The location of the transmitter and animal can be determined by triangulation, which requires the collection of transmission data from three or more different locations around a single point. VHF tracking is a relatively cheap and low-cost method of biotelemetry that can also be long lasting due to the low-power requirements of transmitters. It can be used on a variety of animal species, from insects to large mammals, which makes it very effective and widely applicable. However, VHF tracking is incredibly laborious and requires on-site tracking, since the transmission signal can only be received nearby with an antenna. Furthermore, triangulation of data can be extremely tedious and while the initial cost of a device can be inexpensive for VHF tracking, the individual cost of each data point can become extremely costly [4]. 3.1.2. Satellite Tracking

Figure 2: Various species fitted with Argos transmitters, demonstrating its widespread use.

Satellite tracking offers an immediate advantage to VHF tracking in that it allows for global tracking. This is mainly due to the existence of the ARGOS satellite system, which is almost universally used for wildlife tracking. Satellite biotelemetry has been around since the mid-1980s, after an agreement between the French Space Agency, National Oceanic and Atmospheric Administration (NOAA), and National Aeronautics and Space Administration (NASA) allowed ARGOS to be used exclusively for the collection of environmental data [5].

ARGOS satellites identify signals sent by transmitters that are called Platform Transmitter Terminals (PTT), which have been miniaturized over time to allow attachment to animals. They do so using the Doppler effect, which allows the satellites to iteratively integrate signals, using the Doppler shift to measure the receive frequencies of incoming messages. Finally, the location of the PTT is estimated based on the satellite location combined with these integrated Doppler shift signals.

Unfortunately, while the ARGOS satellite system allows for global tracking, PTT units are extremely expensive and can be quite inaccurate. The use of Doppler shift signals means that it is hard to obtain a successful location fix, as Argos processing centers require multiple messages from a transmitter to make the proper estimations. Furthermore, due to the scarcity of satellites in the ARGOS system, only a limited number of fixes can be acquired in a day and researchers must hope that a satellite passes overhead and obtains a successful fix for accurate data.

3.1.3. GPS Tracking

Figure 3: A dog fitted with a GPS collar. GPS biotelemetry has become so successful that it has even been commercialized for everyday use.

Since the launch of the Global Positioning System (GPS) in 1993, it has been widely used and adopted in wildlife tracking due to its widespread availability and ease of access. Compared to ARGOS, GPS technology utilizes over 24 satellites to provide location data to users. If a GPS receiver picks up signals from three satellites (using triangulation), the receiver can be located in two dimensions (latitude and longitude). If it instead picks up signals from four satellites, the receiver can be located in three dimensions.

GPS data can be stored and/or received in multiple ways. First, the data can simply be stored on the receiver over time until the animal carrying the tag is recaptured and the data is retrieved. Second, the data can be wirelessly downloaded off of the tag to another receiver. Finally, the GPS data can be relayed over the ARGOS satellite system, which allows the data to be globally accessed.

The use of GPS has revolutionized biotelemetry and made it much easier, allowing researchers to obtain data anywhere in the world with excellent accuracy. Furthermore, researchers can obtain truly continuous data without having to wait for a satellite to be overhead. However, GPS systems can still be quite expensive, especially when combined with the usage of satellite transmission. GPS tracking devices also consume lots of power, due to the high power demands of locating and determining a GPS satellite fix. 3.1.4. Future Developments in Tracking Devices Much of the development in tracking devices is currently focused on optimization of current devices, which include battery optimizations and size reductions. As power consumption becomes more optimized, the inclusion of sensors that will allow researchers to not only track location but also study environmental conditions will increase which will allow the simultaneous study of not only wildlife behavior, but also wildlife biology and ecology. However, there are specific developments in animal tracking devices that could be useful.

3.1.4.1. Nanotechnology Researchers have explored using nanometer-sized fluorescent probes called quantum dots in order to study microorganisms including zooplankton and phytoplankton [6]. Controlled experiments showed that the implantation of these devices did not affect the overall behavior of the affected animal species and may allow researchers to study microorganism response to light, food, and predation, all which could not be studied before in such microorganism animal species. 3.1.4.2. Transceivers Currently, receiving biotelemetric data requires the offloading of data onto land-based centers, which requires some sort of physical interaction with tags or receivers. However, with the use of transceivers, or devices that act as both transmitters and receivers, researchers plan to have tags communicate with each other or to satellites in order to increase the ability to both transmit and receive data. 3.2. Development of Low-Cost Wildlife Tracking Devices While wildlife tracking has become more accessible due to GPS and satellite systems, these systems are still extremely expensive and make it hard to track many animals at once. Furthermore, in developing countries, it can be near impossible to acquire devices or justify the cost of a device when it can easily be lost or broken by animals in the wild. For this reason, it has been the focus of researchers to develop low-cost tracking devices using existing technology. Now that open-source hardware and software have become so widespread, it has become increasingly easy for researchers to create their own devices.

In multiple occasions, researchers have taken existing devices that contain a GPS unit and a transmission system and modified them to create a low-cost tracking device [2, 7, 8]. A focus on many of these devices is the use of cellular communications, which is now widely accessible and much cheaper than transmitting data over the ARGOS satellite system. Devices can also be easily modified to the need of the researcher and can include sensors that allow for tracking of further data than just location, including speed, temperature, altitude, and battery status. Finally, specific software is not required to access data, and data is often published on a simple Internet-connected web browser or application. Compared to current tracking devices, which can cost upwards of thousands of dollars, most of these low-cost devices can be built or modified for under US$500. Furthermore, the use of existing accessible GPS devices meant that accuracy or resolution did not have to be sacrificed in the creation of these low-cost devices. The main disadvantage of these devices are the time required to build each device and the lack of commercial optimization in devices that may require additional maintenance or adjustments compared to the typical tracking device.

4. Conclusions

Biotelemetry is a developing field that is important in the study of wildlife behavior and movement. Since the formal start of biotelemetry in 1963 with the use of VHF devices, the development of the ARGOS system and today, GPS devices have allowed biotelemetry to become more accessible and widespread in this field. While these devices are extremely expensive, there is widespread movement to make devices cheaper. With continued research into the field and into future technologies, it will be

incredibly exciting to see costs plummet in the construction of these devices to allow for the widespread study of animal species. Now, more than ever, the future of animal tracking is that of the simple hobbyist who can buy a GPS unit and a microcontroller to build a device that is just as reliable and accurate as a commercial system. The use of these modular, customizable systems will not only allow researchers to track more than just location, but also learn more about the behaviors of animals which have yet to be explored to this day. With the further development of biotelemetric devices, the still unknown world of wildlife biology will become more familiar, even to the microorganism scale.

5. Acknowledgements

Thank you to Dr. Gartner, the Swanson School of Engineering, and the Office of the Provost that provided the original funding for the project that led to this article. Thanks also to the Pittsburgh Zoo & PPG Aquarium for the support throughout this project as well and for the opportunity to dive into this exciting world of wildlife research.

6. References

[1] B. Thomas, J.D. Holland, E.O. Minot, Wildlife tracking technology options and cost considerations, Wildlife Research. 38 (2011) 653-663.

[2] C.A. Zucco, G. Mourao, Low-Cost Global Positioning System Harness for Pampas Deer, J. of Wildlife Management. 73 (2009) 452-457.

[3] W.W. Cochran, R.D. Lord, A Radio-Tracking System for Wild Animals, J. of Wildlife Management. 27 (1963) 9-24.

[4] A. Markham, On a Wildlife Tracking and Telemetry System: A Wireless Network Approach. 2008.

[5] R. Farve, Demonstration of Satellite/GPS Telemetry for Monitoring Fine-Scale Movements of Lesser Prairie-Chickens, United States Department of Agriculture. 2002. Accessed 24 Oct 2019. https://www.fs.fed.us/t-d/programs/im/satellite_gps_ telemetry/wildlifetrackingtelementry.htm

[6] M. Lard, J. Backman, M. Yakovleva, B. Danielsson, L. Hansson, Tracking the Small with the Smallest – Using Nanotechnology in Tracking Zooplankton, PLoS ONE. (2010).

[7] M. Fischer, K. Parkins, K. Maizels, D.R. Sutherland, B.M. Allan, G. Coulson, J.D. Stefano, Biotelemetry marches on: A costeffective GPS device for monitoring terrestrial wildlife, PLoS ONE. (2018).

[8] B.M. Allan, J.P.Y. Arnould, J.K. Martin, E.G. Ritchie, A costeffective and informative method of GPS tracking wildlife, Wildlife Research. 40 (2013) 345-348.