We get asked that a lot, and for good reason. Everyone wants to find their animal, and they want to know how close they need to be before they can pick it up on frequency before calling it a day. The answer varies; there are numerous variables, and the variables are always changing!

Let’s start by saying that VHF tracking is line-of-sight. That means that the receiving antenna has to “see” the transmitting antenna before a signal can be heard, and vice versa. Anything that is in the way of that line-of-sight path will attenuate, or degrade, the signal. This includes light or heavy brush, trees, and most definitely, mountains. And if the animal goes behind a crop of rocks or decides to lay down, there goes your range.

Many times, the best way to increase range is to hold the antenna higher up off of the ground. To really increase range, get in an airplane and track – you’ll have excellent line-of-sight and very good range, many miles in fact.

Another big influence on range is the type of receiving antenna used in your field work. One simple way to increase range is by using an antenna with more elements on it, e.g. a four element antenna instead of a three element one. A directional type antenna will provide better range than a dipole antenna, which only has one element. An excellent paper, Selecting Receiving Antennas for Radio Tracking is available on the ATS website.  

Also, using a narrow band receiver designed specifically for telemetry will increase range, especially one that includes digital signal processing (DSP) capability. The ATS R4500 series of telemetry receivers are a good example. Their band width is 4 MHz, and a DSP chipset is used; better performance than a receiver with 8 or 16 MHz band width and lacking DSP.

Finally, the transmitter design itself will influence reception range. A longer antenna will increase range, and use of a three stage circuit will too. ATS offers the option to include a three stage circuit in some models. This will provide you with a stronger signal than a standard transmitter circuit, but at the expense of battery life, since the power output is higher.

If you have additional questions about how you might increase the range of your radio telemetry system, please call us at ATS.

Mule deer researchers in Nevada are utilizing ATS’ G2110E Iridium/GPS Location Collar to learn more about mule deer migratory corridors and migration behavior. Currently, over 150 Iridium collars are deployed in Nevada, with more recently deployed in winter 2012-13. 

Researchers there are able to collect fixes as frequently as one every 15 minutes, or as few as one per day. The variable programmability of ATS' Iridium collars has allowed researchers to increase fix intensity during peak migration periods, and decrease fix intensity during times mule deer remain largely sedentary on winter and summer ranges. 

The collar's flexibility of programming, and remote programmability via e-mail command, have allowed researchers to learn several things about their mule deer including: summer range, winter range, migration corridors, migration timing, migration triggers, migratory behavior, foraging areas, and fawning areas. A couple of the migration corridors in Nevada have been demonstrated to be over 120 miles long, as shown in the image bottom left. 

Another question currently being addressed with the Iridium collars is “how do mule deer respond to novel disturbance along their migration corridor?” Hourly fix intervals have allowed researchers a better understanding of the potential energetic cost associated with navigating novel disturbance that bisect their migration corridors. The image at bottom right shows how five deer moving through a disturbed area moved differently before and after the disturbance than they did while moving through the disturbance. This type of information is essential to understanding the potential impacts of migratory corridor disruption.

This application is just one way ATS' Iridium collars can benefit wildlife research. To learn more about how ATS can help you meet your research objectives, call your ATS Consultant, or go to the ATS website and request a same day quote today!

Because condor range expansion could one day lead to interactions with renewable energy facilities, the ReCon system will help to address this concern. The system has now been fully tested and proven effective, and is available to researchers from Normandeau Associates.

This is just one example of an integrated system using the R4500 line of standard and coded receiver-dataloggers that have been deployed around the world for the study of aquatic and terrestrial animals. The R4500 is also at the heart of ATS’ system for tracking deer and fawns using coded transmitters, which is in use throughout Colorado today.

For more information on how an R4500 system can benefit your research, contact an ATS Consultant.

 Schematic of Normandeau Associates ReCon system

View of ATS model R4500SD Receiver-Datalogger used in the Condor Detection System, ReCon (pdf).

We thank Kevin Smith of Drexel University for this guest post:

The Northern pine snake (Pituophis melanoleucus) is a state threatened species in the New Jersey Pine Barrens. Due to the cryptic and fossorial nature of this species, there is a lack of data on their early life behavior and dispersal.  An understanding of first season life history traits from hatching to ingress is particularly difficult to monitor.  

Without field observations it is difficult to elucidate key developmental processes, such as shedding rate, feeding rate, diet preference, habitat preference, dispersal patterns, and the spatial ecology after leaving the nest.

The Laboratory of Pinelands Research, under the direction of Dr. Walter F. Bien at Drexel University, has been studying the Northern pine snake for over a decade in collaboration with the NJ Department of Environmental Protection, and the New Jersey Air National Guard at Warren Grove Gunnery Range.

Dr. Ron Smith and Dane Ward have collectively implanted and radio tracked over 70 individuals, investigating their spatial ecology and distribution. Until recently, the use of implanted radio transmitters was only applicable for fully grown adults, and external transmitters are not appropriate for semi-fossorial constrictors as they interfere with normal snake behaviors and readily fall off this active species.

Last year, however, as part of Kevin PW Smith's doctoral thesis, we performed the first surgical transmitter implantation in eight P. melanoleucus neonates using six ATS model R1635 and two model A2414 transmitters.  

Both models were successful in tracking pine snakes in the first stages of life. In collaboration with the New Jersey Conservation Foundation at the Franklin Parker Preserve,  we monitored neonate activity daily, and recorded environmental and behavioral data. This season, an additional ten neonates will be implanted with ATS model R1635 transmitters and tracked daily.  

Being able to make daily observations on a previously secretive and understudied life stage in situ has given us insight to a wide range of behaviors, including dietary patterns, shedding schedules, and micro-habitat usage.  

Each day of new data has helped fill in vital gaps of the life history of this species. This research facilitates our ability to better plan, recommend, and execute more conservation strategies for this threatened species.

 Photo credit: Kevin Smith

If you are coming up short on usable frequencies in your field studies, there is an answer. At ATS we've developed a coded tracking system that will allow you to track 100’s of terrestrial animals, using the fewest frequency channels. In addition to using fewer frequencies, tracking work can be accomplished more accurately, faster, and with better range than with standard VHF tracking systems.

For many years fish researchers have used coded tagging schemes in their studies, allowing them to track thousands of fish in a compact area, such as a river. Realizing that terrestrial researchers were facing a limitation on the number of frequencies available in the spectrum, ATS engineers set out to develop a system to utilize a coded ID system to track animals on land.

At the heart of the system is ATS' proprietary coding scheme and R4520C Receiver-Datalogger, which enables the researcher to track and identify up to 25 tags sharing a single frequency. While tracking in the field, whether on the ground or in an aircraft, one is able to choose an individual animal within the group, hear only that tag, and locate it with pinpoint accuracy. This receiver features digital signal processing algorithms and so provides excellent sensitivity, allowing target detections faster and at twice the range of other receivers. 

This model is much different then the standard models that make up the R45xx series of receivers. Below is a portion of the receiver's control panel, which shows a view of the keys used to hear or silence certain transmitter ID's. Not shown is the LCD display which will show up to nine of the frequencies within range. 

The other component of the system is the VHF encoded transmitter(s). Each transmitter is assigned a discrete code, (e.g. C-31), but will be assigned the same frequency (e.g. 164.100) on up to 25 other transmitters.

If you'd like a more in depth explanation of coded tracking systems for terrestrial applications, a white paper is available on the ATS website.

To learn more about how ATS can help you meet your research objectives, call your ATS Consultant, or go to the ATS website and request a same day quote today!