Station and Tag Selection Guide
This page explores some questions that should be considered before installing a Motus station. For more information, see:
What movements am I trying to detect?
As students of migration ecology, we ultimately seek the ability to know everything about all individuals at all times. Unfortunately, the technology required to do this for most flying migratory animals, particularly the smallest bodied ones, does not exist. Therefore, biologists have to use a combination of complementary tools such as tracking-based geolocators, GPS and GSM, GPS and Geolocation data loggers, as well as isoptopic, genetic, and good old bird banding/ringing to discover the complete life histories of migratory animals. While often viewed as having competing value, these tools are undeniably complementary, and researchers need to employ the best tool for the job given the specific questions and study system in mind.
What is most unique about Motus is that it provides an opportunity to track the widest variety of the smallest animals possible, today, at local, regional, or hemispheric scales depending on the location and species in question. And best of all, almost anyone can get involved in one way or another – Motus is the ultimate hands-on community science project.
Another important differentiation between automated radio telemetry and other technologies available is that the temporal precision of the data can be much greater with radio telemetry as tags can repeat their signals as quickly as every 2 seconds. This extremely high temporal precision can allow for exceptionally detailed examinations of an animals behavior, movement patterns, direction and speed of flight.
The selection of specific tag type will largely depend on the spatial temporal scale of your study as well as your study species and geography.
The study location may largely determine what type of data you can expect, and which tags to use. When setting up your study, it’s important to consider how your tags may be detected by receivers in your area of interest. One tactic employed by the Northeast Motus Collaboration is to build a receiver ‘fence’ over a geographic area such that any tagged animal passing through it will get detected. In Ontario, where many more stations are available, there is a grid of stations (or series of fences) to allow for better spatial resolution of movements. In the end, you will need to decide what works best for your region based on migratory flyways, foraging locations, your goals, funding, and the location of nearby receivers.
Go to the receivers map to see all currently active receivers, what frequency they operate on and which type of tags they can detect. Keep in mind that these receivers have been deployed by various researchers who check their stations at different times. It’s helpful to check the ‘last data processed’ to get an idea of how often these stations get checked – you don’t want to be stuck waiting for a station you don’t own to get checked! In addition, stations that haven’t been checked in a long time (6 months to a year) may be in various states of disrepair so it’s also best not to rely on these stations before contacting the project manager.
Motus supports two types of uniquely coded radio transmitters: NanoTags™ manufactured by Lotek Wireless Inc, operating on frequencies 166.380 MHz (Western Hemisphere), 150.100 MHz (Europe), and 151.500 MHz (Australia), and LifeTag™ and PowerTags™ manufactured by Cellular Tracking Technologies (CTT) operating on 434 MHz globally. The two tags use fundamentally different transmission and coding systems. Nanotags tags use amplitude modulation, or AM, whereas CTT tags us frequency modulation, or FM. Nanotags emit 4-bit pules that encode a unique ID in the time difference between these pulses, called Pulse-position Modulation (PPM). CTT use frequency-shift keying (FSK) which flips between two similar frequencies to encode a binary “1” or “0”, with a total of 64 of these bits per transmission.
The distribution of stations listening for either tag is not uniform, so collaborators should consult the Motus Receiver Map to confirm which frequency stations are operating on throughout the network. When communicating with Lotek or CTT, be sure to explicitly state that you want your tags/system to be compatible with Motus.
It is simple to outfit some Motus receivers to be dual-mode in order to “listen” for both of these tag types. We recommend that stations be configured this way whenever possible in order to support the greatest number of researchers.
There is a lot of detail about these two tags that can’t all be explored here, but the table below summarizes the major differences. Contact Motus, or the tag providers above for more information.
|Frequency||150.1, 151.5, or 166.380 MHz||150.1, 151.5, or 166.38 MHz||434 MHz||434 MHz|
|Lifespan||Long (20 – 2000 d)||Unlimited||Unlimited||Long (180 d to yrs)|
|Daily active period||24/7 or alternate 12-hour on/off||24/7 (battery and solar powered)||Only in direct sunlight (solar powered)||24/7|
|Weight||0.15 g – 3.00 g||1.4 g and up||0.44 g and up||0.33 g and up|
|Smallest bird (%3 body weight)||5.0 g||46.7 g||14.7 g||11.0 g|
|Possible number of unique tags||>36,000*||>36,000*||~4 billion||~ 4 billion|
|Burst intervals||~2-40 seconds||Similar to CTT (may diminish with power loss) [needs more information]||2 seconds (configurable)||Programmable: from 1 sec up|
|Current number of compatible Motus Stations||850+||850+||40+||40+|
|Compatible with CTT Receivers||SensorStation with FUNcube Dongle only||SensorStation with FUNcube Dongle only||Yes||Yes|
|Compatible with Lotek Receivers||Yes||Yes||No||No|
|Compatible with SensorGnome Receivers||With FUNcube dongle only||With FUNcube dongle only||With CTT Motus Adapter only||With CTT Motus Adapter only|
|Price||~$200 USD||~$200 USD||~$200 USD||~$200 USD|
|Discount||Contact Lotek||Contact Lotek||5% for 20+
10% for 30+
|5% for 20+
10% for 30+
|* This number is calculated by multiplying the number of unique ID’s emitted by Lotek tags (517) with the number of unique burst intervals available (70). These burst intervals range from 2.3 to 39.7 seconds, which corresponds to the number of primes between 23 and 397 such that no two burst intervals overlap with one another.|
Will my tags be detected upon release?
An important consideration that is often overlooked is where and when you expect the first tag detections to occur. We recommend researchers try to always deploy tags with the assistance of a manual receiver from the manufacturer of choice, and/or in the vicinity of a Motus station so you can confirm the tags were working and detected immediately upon release. Then one can can confirm that they’re being detected by the nearby station in case there is an issue with missing data. This type of local information also garauntees some immediate results from the animal you’ve tagged in terms of duration spent at that specific site, and in the case of migrants perhaps information on migratory timing and direction. In remote settings away from a station, one should always have a manual receiver.
It is also very important to ensure stations are operational and can detect your tags by conducting a tag test prior to tag deployment.
Do I need a permit?
The tagging of animals typically requires several permits and approvals to be in place beforehand:
- Animal Care Approval from an institution or approved organization
- Federal permit for species and methods under their jurisdiction
- Provincial or state permits for species under their jurisdiction
- Various federal, provincial or state species at risk for species under their jurisdiction
How do I tag animals?
The method of tag attachment to an animal depends on the type and lifespan of transmitter being used, the study species/system, and the environment in which the transmitter is being deployed. Click here for a guide on tag deployment methods . Please note this document is currently under revision.
What is the purpose of this station?
Motus stations provide spatial temporal information on the position and behaviour of migratory animals. Most stations are deployed strategically to fulfill the needs of a specific research project; as part of a regional network to provide broad landscape scale fences, or walls; or more opportunistically distributed to serve at specific sites of interest that may have a scientific, conservation, or education and outreach value (see Motus Education).
The placement of a Motus station largely depends on its purpose; what you intend to detect in relation to specific landscape features within the estimated range of the station. For instance, projects seeking to learn more about movements through a corridor will benefit from having stations deployed in a manner that creates a ‘fence’ (an array of receivers in a line), detecting any animals that pass through it. In this instance, only two antennas may be needed per station/frequency to provide useful coverage. However, if the interest is more on the use of a specific habitat or geographic feature, it may be better to circle an area, or create a grid of stations or nodes, or place a single station in the centre of the area you wish to monitor animals within. It is seldom necessary to have antennas pointing in all directions since three or four antennas is usually enough to cover the area of interest. See Station Placement for more details.
Selecting the right antenna for the purpose of the station and the type of tags you intend to detect is incredibly important. Antennas are optimized for reception on a particular radio frequency. Therefore, each tag type requires its own antenna; an antenna optimized to detect Lotek tags will not detect CTT tags, and vice versa. Wherever possible we recommend installing “dual-mode” stations outfitted with antenna and a receiver that can detect both Lotek and CTT tags. A dual-frequency antenna is under development, but for the time being, dual-mode stations (those that can listen for both Lotek and CTT tags) must have two different types of antenna in place.
A variety of antenna options exist for VHF telemetry. To date, collaborators have used 3, 5, 6, and 9-element Yagi directional antennas, and single-pole/ j-pole/omni-directional antennas. Generally the greater the number of elements, the longer the detection range and more narrow the detection beam. The fewer the elements, the shorter the detection range, but the broader the detection beam. Omni-directional antennas are best suited for determining species presence-absence patterns (e.g. seabirds at a colony), or for detecting birds in close proximity to stations (within a few hundred metres), but not for providing directional information (e.g. departure directions of songbirds from a stopover site).
Large Yagi antennas are useful for making receiver fences and grids since they can be spaced as far as 30 km apart with antennas pointing towards each other to capture animals passing in between. Smaller Yagi antennas are typically used for manual tracking, or for monitoring animals within a small study area. CTT Nodes have small omni antennas with a line-of-sight (LOS) range of around 1.4 km which if distributed in a grid can provide highly accurate location estimates.
Not all stations are created equal. Some will primarily achieve local objectives, others are part of regional networks, and others strategically placed at migration hotspots to serve the collective needs of the entire network. At the end of the day, all stations collectively work together to make up the Motus network and provide data to far more projects than your own. Motus is the ultimate hands-on, community science project.
Ideally, adjacent stations will complement one another; that is, they operate on similar frequencies and have antennas which point towards one another to provide detections of tagged animals as they pass between the stations. Multiple receivers can be employed to build a receiver ‘fence’ to detect any animals that may pass over a geographic area. Examples of these can be seen in the North-eastern US and along the North Sea of Europe. In Ontario, where many more stations are available, there is a grid of stations (or series of fences) to allow for better spatial resolution of movements. On study sites like Sable Island and Bon Portage Islands in Nova Scotia very small grids have been used to study local movements. In the end, you will need to decide what works best for your region based on migratory flyways, foraging locations, your goals, funding, and the location of nearby stations.
When selecting a site, it’s important to consider how the landscape features will affect the range of your antennas. Generally, higher stations have a greater range and detection probability of passing animals, but have a more limited probability of detecting local movements. In most instances, stationd should be placed in the highest elevation possible within the area of interest, ensuring there is a clear line of sight in each direction you wish to point the antennas. It’s also important to ensure there aren’t any obstructions immediately behind the antennas (within a few meters), especially metal surfaces like roofing.
Antennas can receive interference if placed too close to metal objects or other antennas, or sources of electromagnetic noise (Air conditioners, generators, lawn mowers). Depending on frequency and location, radio interference from third-party broadcasters and cellular can also be problematic. Some online tools exist to locate licensed radio broadcasters by location (click here for Canadian stations).
Yagi antennas should be vertically spaced according to their direction and frequency. Make sure you have ample spacing between your antennas and any sheet metal, such as roofing. The typical figure for minimum spacing and metal roofing is 1 full wavelength. Yagi antennas that point in opposite direction (parallel) will interfere with each other if spaced too closed together, essentially eliminating the directionality and severely impacting the detection range. Antennas that are parallel (180 degrees) should be at least ½, but best at a whole wavelength apart. Antennas that are perpendicular (90 degrees) should be at least ¼ wavelength apart.
|9-element Yagi||Lotek||166.380 MHz||1.80 meters|
|9-element Yagi||Lotek||151.500 MHz||1.98 meters|
|9-element Yagi||Lotek||150.100 MHz||2.00 meters|
|9-element Yagi||CTT||434 MHz||0.69 meters|
Antenna Mounting Structure
Motus stations have been built on just about anything – lighthouses, towers, trees, cars, drones, planes, ships, buoys, bamboo masts, and a just about every type of building you can dream of. Click here for a list of example stations.
The actual structure doesn’t necessarily matter as long as it’s strong, elevated enough to provide a clear line-of-sight, and the antennas are not mounted close to sheet metal or other antennas (see above). The easiest and perhaps cheapest method is often to use a pre-existing building or structure upon which masts or antenna can be affixed to existing railings, or on the side of buildings where a DMX-style structure can be mounted. Installation can be tricky, but once it’s set up there won’t be much maintenance.
In remote locations where there aren’t any buildings to attach towers, one can use a tripod and mast like those manufactured by Wade Antenna, or other self-standing tower design. These towers must be guyed (3 lines per 10-foot section) and anchored (1 anchor per guy or just 3 strong anchors). These structures are more sensitive to wind and ice than the DMX-style structures so regular maintenance will be necessary. See station setup guide [in development].
We can’t stress enough the importance of excess supports in any setup situation. Use more and stronger guy wires than you think you need, more waterproofing, more wall mounts bigger batteries, bigger solar panels, and strong gauge, galvenized or stainless steel materials (especially in marine environments). It will cost you more in the end per setup, but shortcuts will often cost you more in the long-term.
The following list includes equipment commonly used across North America. For equipment used in other regions, please contact us.
- Against wall of a building: DMX tower (36′)
- Non-penetrating roof mount:
With all these mounting method in mind, we recommend you contact your local supplier for Wade Antenna to find the best solution for your location.
Providing mains power to a station increases reliability and reduces worry and cost per station. All Motus stations – whether Sensorgnome, Lotek, or Sensorstation – simply require regular 120 or 240 V AC supply through a regular USB power adapter, such as a phone charger. We recommend a good-quality power adapter, such as a cell charger, and a surge protector in regions where power surges are frequent. Special adapters may be required for some Lotek D-series receivers.
Adding a solar panel, battery, and charge controller adds at least $500 USD in initial expense, not including potential troubleshooting time and maintenance costs. If you’re able to find a reliable source of AC, that’s best. For an off-grid power supply, you will want at least 100-Watt panel for a year-round station with 3 antennas. The battery needs to be a deep-cycle sealed lead-acid battery (24 or greater AGM preferred – recommend Trojan or equivalent) with at least 70 Amp-hours (Ah) of storage, 100+ is ideal for high latitude locations. As for charge controllers, we use the SunSaver SS-10L-12V or greater depending on the size of the solar panel. Charge controllers must have a low-voltage disconnect to eliminate chance of draining a battery too low.
The specific battery and solar panel brands will depend on locality so we suggest you contact your local dealer for advice.
Both SensorGnomes and CTT SensorStations support automated uploads to Motus.org, eliminating the need for regular site visits to download data manually. In addition, live web interfaces can be viewed for either station, allowing for users to remotely diagnose issues that may have occurred. However, the ability to connect to our server will depend on whether internet or the right kind of cellular network is nearby.
You can connect Sensorgnome-based receivers (see below) to the internet via Wi-Fi or Ethernet cable. Some collaborators have installed their own cellular internet modems adjacent to their station to give their Sensorgnome internet. Importantly, internet must be password-protected with WPA-2 encryption for Wi-Fi connections.
CTT SensorStations can only connect via Ethernet cable or cellular network, depending on which cellular module is installed on the board.
Lotek SRX800-MD4 receivers can be configured to allow for remote downloads and customization, but data must still be manually be downloadded from Lotek’s website and then uploaded to Motus.org.
It’s worth contacting experienced researchers in your region for help with station procurement and setup – certain components often have reliable local suppliers. A list of regional coordination contacts can be found on our Regional Coordination Page. You can also find contact information about individual researchers in your area by going to our receiver map and selecting the receiver of interest. A popup with information about the receiver will appear – click on the project name to get to the project page. The project page should give you the names and contact of the lead researchers involved. In addition, we recommend you get in touch with local radio experts, such as a ham radio club.
There are three types of receivers compatible with Motus that can be purchased, or built yourself in some cases: Lotek Wireles Inc (SRX600, 800 and D-series receivers), CTT Sensorstation and Nodes, and the open-source SensorGnome.
Sensorgnomes can be purchased from Compudata or RFS Scientific or built with the following instructions. Note these instructions are very outdated and require revision. New instructions will be posted in the near future.
|Compatible with Lotek Tags||Yes||Yes||Yes|
|Compatible with CTT Tags||Yes||Yes||No|
|Base Price||$625 USD||$389 USD board only1||[Contact Lotek]|
|Accessories||DC power converter (for solar installations): $45-75 USD||Waterproof case: $45 USD
Wi-Fi Module: $30 USD
Cellular Module: $50 USD
Power supply (for AC installations): $25 USD
Bulkheads (1 required per antenna): $10/each USD
Health Reports Data Plan: $5 USD/Month
Automatic Upload Data Plan: $5 USD/Month Base + Data
|Price per Lotek-compatible antenna dongle||$200 USD||$200 USD||$0 (included)|
|Price per CTT-compatible antenna dongle||$100 USD||$0 (included)||Not compatible|
|Remote data download and diagnostics? (Requires internet)||Yes||Yes||Yes|
|Internet connectivity?||Ethernet and Wi-Fi; cellular modem can be installed separately||Cellular2 OR Wi-Fi; Ethernet||Cellular (modem purchased separately)|
|License||Open-source hardware and software||Open-source hardware and software||Proprietary|
|Used for manual tracking||Possible with added battery pack, but not well tested.||No, but see CTT Locator||Most models can be used for manual tracking.|
|1 Price does not include cost of: Wi-Fi module; cellular module; data plans; case; power supply; bulkheads (1 required per antenna); or testing time.
2 CTT charges $5/month base plus data costs for cellular data plans and an additional $5/month for station health reports. Contact CTT for more details.
3 Cost for self-built SensorGnomes is estimated to be ~$150 USD without dongles, but prices may vary. Instructions on building SensorGnomes can be found here, but note these are very outdated and require revision. New instructions will be posted in the near future. We do not recomend collaborators build their own SensorGnome without prior experience.