Fig. 4From: Sperm collection in Black-legged Kittiwakes and characterization of sperm velocity and morphologyWithin- and between-male variance in sperm morphological traits based on 7–16 sperm cells (mean ± SE: 10.1 ± 0.5) for each of 20 males. Dots represent individual mean lengths (± SD) ranked in order of magnitudeBack to article page