5/5 Migrating at the right time means migrating in bad weather. Older storks were performing worse at flight to perform better at migration. Whether or not an animal is improving its performance at a task can only be determined in the context of that task.

4/5 Soaring well requires good thermals. Waiting for the best thermals means waiting for summer afternoons. But if storks don’t migrate until the weather is good, they miss out on the breeding season.

3/5 We found that, rather than showing a learning curve, older white storks performed worse in almost all flight metrics. How do we justify this?

2/5 We tracked 151 storks over up to 8 migrations (at 1 Hz!) to ask whether they improve their soaring skills to migrate efficiently. We identified > 55,000 soaring & > 6,000 flapping events that allowed us to compare flight across ages & seasons.