Passive Integrated Transponder (PIT) tags help scientists track individual organisms by providing a reliable lifetime 'barcode' for an individual animal.An important aspect of understanding animal migration is the ability to track and recognize individuals over time and space . Technological advances made over the past decades now allow us to digitally track our study animals in ways that just a generation ago would have seemed unfathomable. Radio and satellite telemetry have revealed a lot about animal movements, but are limited by the need for batteries, whose weight sets a ceiling on the size of the animal that can be tracked External tags (e.g., ear and leg tags, dart tags, painted marks, scale clipping) have also facilitated animal tracking. These are relatively cost-effective, but their external nature makes them susceptible to being lost, scratched, rendered illegible upon recapture, and also subject to human error while being read , often causes the animals pain and has thus been viewed as inhumane . So what should you do if you want to recognize an individual animal over the course of years? Here, we use, benefits, and limitations of internal passive integrated transponder (PIT) tagging to study animal movement. Please kindly check below details.