The Rainier-S20 is a solar-powered, GPS-equipped Argos transmitter (PTT) tag specifically designed for birds. The Rainier-S20 is suitable for birds weighing as little as 650 grams to be tracked with GPS precision and accuracy over land and sea for multiple seasons.



The Rainier-S20 has a very low profile and sports a powerful and flexible antenna, smooth surfaces, and rounded edges with no sharp/cutting finishes. The design helps minimize mass, drag, and risk of injury to the bird.

The tag’s intelligent, low-power design incorporates our latest Argos-certified transmitter, a 48-channel GPS receiver, temperature, battery voltage, tilt, and accelerometer sensors. A non-volatile memory with the capacity to store up to 58,000 locations (about 6.5 years of GPS locations based on one location per hour). The small, solid cast 20 g package is waterproof and tested to 100 m depth.

Want free tags? Learn more about our Early Adopter Program

Key Features

Here are some of the key features of the Rainier-S20.

  • Specific avian design—the “smaller is better” approach to design means there is no need for a bigger tag on a bigger bird. The rounded edges of the tag allow for streamlined aerodynamics while preventing any bird damage from sharp cutting finishes. We also offer either harness loops or holes for attachment depending on your preference.
  • Argos antenna—minimally intrusive, low-lying antenna exiting the rear of the tag is lightweight, highly robust yet super flexible. The antenna is securely anchored in epoxy resin and withstands over 100 pounds of tensile force ensuring it will stand up to abuse from birds.
  • Solar cells and power—solar cell design and circuitry efficiencies allow for improved charging in low light conditions and partial feather coverage.
  • Flexible calendar scheduling—hundreds of duty cycles if required, not limited to just five.
  • Smart algorithms differentiate shifts in day length and times of civil sunrise and sunset—Rainier-S20 tags’ smart day/night algorithms accurately calculate civil sunrise and civil sunset to the minute for any location on the globe. The algorithms are integrated within the scheduling and automatically and dynamically control the scheduling which is particularly impressive on migratory birds crossing multiple time zones or on resident birds as the seasons change.
  • External communications port with multiple benefits including:
    • Administer your own tag setting through Wildlife Computers Tag Agent Software
    • Charge your tags indoors with visual LED feedback
    • Download the entire tag archive if it is located after deployment (it does not need to come back to Wildlife Computers)
  • Transmitted locations and status messages—the Rainier-S20 method of sending GPS locations and other data through Argos builds on Wildlife Computers more than 20 years of experience of sending information via satellite in the most challenging marine environments and time stamps each to within two minutes of the actual fix. Status messages and cumulative status data sent can be used to infer the basic health of the tag.

User Guide

Rainier-S20 Quick Start Guide

This user guide gives you all the essential information needed for interacting with, configuring, and deploying this tag.

64-bit USB Driver 18-Dec-2017

Driver for the Wildlife Computers USB communications cable. A 32-bit version is available on our Downloads page.

Tag Agent

Administer settings to your tag.


Below are the physical specifications of the Rainier-S20.

Dimensions(LxWxH)56 mm x 18 mm x 14 mm
Tag weight (excluding neoprene)20 grams
ConstructionSolid cast/hermetically sealed in biologically inert epoxy resin
AntennaGPS patch antenna embedded. Argos antenna 200 mm. Protrudes from back edge of transmitter at 30° to the horizontal
Pressure RatingTested to 100 m depth
Memory/ArchiveApproximately 58,000 GPS locations timestamped to the nearest second
Operating Frequency401.678 MHz
Operating LifeSolar tags >3 years
SensorsGPS, temperature, battery voltage, accelerometer, tilt
GPS AccuracyCoordinate positions are recorded to four decimal places yielding accuracy to +/- 11 m
GPS Channels48
GPS DatumWGS84
Operating Temperature Range0° C to 65° C
CommunicationsVia USB port and Tag Agent user interface software
Battery ChargingSolar or USB
Recovery PingerOptional in future designs, not currently activated
BatteryLithium polymer rechargeable battery
RF Power OutputMaximum 500 mW, typically 200 mW when deployed
Tag On/Off ProtocolUsing a magnet cover
Supply Voltage3.0 to 4.0 volts
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