PHOENICULUS DAMARENSIS - P. PURPUREUS LATITUDINAL GRADIENT IN MANTLE IRIDOSOME DIAMETERS

Abstract

A latitudinal gradient was proposed in microscopic differences in green and violet woodhoopoe mantle iridosome diameters of mantle feathers. Outer iridophore diameters from Green Woodhoopoe P. p. purpureus barbules (0.22 ± 0.03 µm, n = 244) recorded at Morgan Bay were smaller than those from violet barbules (0.28 ± 0.04 µm, n = 248) recorded in Namibia. A latitudinal gradient demonstrated a strong correlation with outer diameters (r=0.99, r2=0.98, n=6, p<0.001). When the outer diameters were divided by body mass the correlation with latitude was marginally significant (r=0.70, Z score=1.49, n=6, p=0.07). This study examined woodhoopoes mantles which may have consequences for energy expenditures.