Fig. 1
From: Testosterone dynamics of migratory birds during stopover

Boxplot illustrating testosterone levels among four groups. Baseline (N = 71), playback (N = 7) and GnRH (N = 7) samples are represented by white boxes and were collected during a trans-Saharan stopover at Yasmina, Morocco. Breeding baseline samples (in gray, N = 6)) were collected at a breeding site in the Middle Atlas Mountains in Morocco. The pink dashed line represents the minimum detection value of the testosterone assay kit.