Andean condors are the heaviest soaring birds, and as such their costs of flapping flight are extremely high. Recent analyses have revealed just how good they are at using rising air to fly without flapping, showing that they flap less than 1% of their flight time [1]. In 2021, we equipped condor fledglings with modern e-obs tags. These provide us with 1Hz GPS fixes, acceleration bursts, environmental parameters and IMU orientation data. Combining these sources in Firetail [2] provides fascinating perspectives on flight effort and soaring strategy and valuable approaches to data annotation. Here, we share first insights into this data.​

​IMU data in combination with acceleration signatures helps us to discriminate stationary (upright, vertical tag position, cmp. right figure: tagged male condor) from takeoff and flying states. These patterns can be identified even from the low-res GPS settings. Activities on the ground like feeding are indicated by associated increases in acceleration. In a context of tag orientation, we can more accurately interpret these movements. ​

These preliminary aspects offer just a taste of what we think may be possible with this kind of data. Fast calibration, contextualization and segmentation tools provided by Firetail unveil the power inherent in IMU-enabled tags. We expect that this detailed view will help us to deepen our understanding of flight strategies, flight costs and how both of these develop with age.​