Keep­ing track over the decades

Popular Science - - CHARTED -

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.

1980s Ar­gos

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.

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