Keeping track over the decades
1900 Bird banding
Scientists systematically wrapped engraved metal bands around birds’ legs but relied on others to recapture the avians to provide info on where they went.
1950s Acoustic telemetry
To track fish, seals, and whales, these tags emit pulses of sound, which are picked up by microphones positioned throughout the animals’ habitat.
1960s VHF-radio transmitters
Researchers using this high-frequency tech to track animals like feral horses had to stay within a few miles of them to pick up signals.
An early satellite-based system used to follow dolphins, albatross, and other creatures, the initial versions couldn’t be reprogrammed from afar.
1990s Isotopic analysis
By scrutinizing the chemical composition of feathers, scales, or hair, scientists can determine the rough origin of the migrating animals they are studying.
1990s Cellphone tags
Though effective for transferring large amounts of information like real-time location data, cellular hardware is energy-hungry and too large for bitty creatures.