The tracker is on the bird. The tracking information is transmitted via cell signal, correct? If the tracker loses cell service and the bird continues to fly, you will not be able to get the current location until it recovers a cell signal. It relies on a cell signal to work.
This is from their website:
Features
* Standalone device powered by a rechargeable lithium-ion 1300 mAh battery that will last up to 12 days.
* Compact and lightweight; the device measures 2.6" L x 1.45" W x .75" H (67mm x 37mm x 20mm) and weighs only 53 grams.
* 6 months of service included for free!
* Carrier agnostic. Not forced to rely on a single carrier's network. Triangulates position using all available networks in the area.
* Includes a specialized SIM card that utilizes network hopping to ensure GPS coordinates can be retrieved 99% of the time.
* Two low-cost service plan options to keep your device activated after your free service period expires.
* SOS button for sending GPS coordinates on-demand. Useful if someone else finds your UAV before you do.
* Uses high sensitivity GPS and assisted GPS and operates on the GPRS/GSM network; accuracy range of 3 ft. to 150 ft.
* Thoroughly beta tested by volunteers on a number of popular UAV's: AR.Drone, RC Eye 450, DJI Phantom 1/2/3, Phantom Vision/Vision+, DJI F450, DJI S1000
* Very reliable even in rural or densely populated areas.
* Will not interfere with your UAV's onboard GPS systems.
* U.S. based phone number.
* Crash proof, non-magnetic, water resistant case.
* Two low-cost service plan options to keep your device activated after your 6 months of service expires.
* 1-year manufacturer's warranty
* FCC and CE certified device; RoHS compliant