Fig. 3. Changes in (A) estimated buoyancy vs depth and (B) depth vs time, and (C–H) body angle (from horizontal), vertical speed, actual swim speed and stroke rate vs depth, for a Brünnich's guillemot (BRGU 13) during descent to 113 m (C–E) and during ascent (F–H). Values are averages over 3 s intervals of recordings at 1 Hz. The depth of neutral buoyancy was estimated as 71 m.