Table 1.

Effective values of the spacing ratio () measured on wing feathers from this work are compared against values obtained from microscopy () of barbs and barbules from the literature for wing feathers and breast feathers. In the last column, an estimate of the half-spacing of defect sites (ℓ_defect) deduced from contact angle measurements is also reported, and its significance is detailed in §3.5 in the main text.

bird species	wing feathers	wing feathers		breast feathers		ℓdefect (µm)
		barbs	barbules	barbs	barbules
African darter	1.28 ± 0.10	1.7a	1.6a	4.5b, 9.9a	7.6a	220 ± 50
reed cormorant	1.24 ± 0.14	4.2a	2.4a	4.3b, 8.5a	2.9a	190 ± 70
great cormorant	1.57 ± 0.15	—		4.8b	—	290 ± 30
mallard	1.84 ± 0.13	5.7a	1.9a	5.9b, 10.6a	2.9a	250 ± 30
European shag	1.91 ± 0.16	—	—	—	—	350 ± 30
common shelduck	1.89 ± 0.12	6.7a	2.1a	11.1a	3.5a	280 ± 30

^a[17].

^b[12].