Fig. 1: Compass-based movement, precision between and within flight-steps.
From: Predicting performance of naïve migratory animals, from many wrongs to self-correction
a Schematic of N migratory flight-steps (orange arrows), based on a single preferred heading (dashed black line), spanning a distance Rmig to a migratory destination (“goal area”, with radius Rgoal). For a given and sufficiently high precision among flight-steps, and ignoring spherical-geometry effects, the probability of successful arrival increases with goal area, the number of required error-free flight-steps, N0, but decreases with migration distance (inset and Eq. (3)). b Within-flight compass precision based on a single (e.g., geomagnetic) cue. The expected initial error in cue detection (angle between dashed orange and black lines) will on average be offset by repeated, e.g., hourly cue maintenance within flight-steps (solid orange line and diamond shapes). c Contrastingly, with transfer to a secondary compass (dashed-purple line, e.g., star compass), the expected flight-step error will exceed cue-detection errors, regardless of cue maintenance (solid purple line and yellow hexagons). Bird icon from http://www.dreamstime.com (ID 16983354).
