Table 1. Morphometric, ecological, behavioral and plumage differences between alexandrinus and dealbatus as given by Kennerley et al. (2008) and their interpretation and score according to the criteria of Tobias et al. (2010).

	alexandrinus	dealbatus	interpretation of difference (as per Tobias et al. 2010)	Score
plumage characters	dark lores in breeding plumage	white lores in breeding plumage	‘major’: different color of strongly demarcated body part	3
	dull dark-brown upperparts	pale brown upperparts	‘medium’: different tone of significant area of feathering	2
	narrower black frontal bar on forecrown of male breeding plumage	wider black frontal bar on forecrown of male breeding plumage	‘minor’: weak divergence in a plumage feature	1
	more dark on lower ear coverts	less dark on lower ear coverts	‘minor’, but potentially co-varying with previous traits	0
	more extensive dark patches on breast side	less extensive dark patches on breast side	‘minor’, but potentially co-varying with previous traits	0
	duller orange crown in breeding plumage	more vivid orange crown in breeding plumage	‘minor’, but potentially co-varying with previous traits	0
biometric characters	shorter wing	longer wing	effect size d = 0.448, i.e. ‘minor’	1
	shorter tarsus	longer tarsus	effect size d = 0.922, i.e. ‘minor’ (score 1), but co-varying with wing length	0
	shorter bill	longer bill	effect size d = 0.340, i.e. ‘minor’ (score 1), but co-varying with wing length	0
ecological and behavioral characters	on average inhabits softer mud along tidal channels	on average inhabits sandier substrate	‘minor’	1
	less active foraging behavior	more active foraging behavior	‘minor’ to trivial, but scoring limited to one trait	0
	horizontal stance; head held ‘hunched’ into shoulders	upright stance; neck visible	‘minor’, but scoring limited to one trait	0
geographical relationship	sympatric on migration and during winter; no information on contact of breeding ranges, therefore tentative score of 0	≥0

Biometric measurements were taken from table 1 in Kennerley et al. (2008). Note that various extremely minor traits are not listed as these would not have qualified for scoring. Also note that vocal differences are not given as none are known. For the score on geographical relationship, see Results. Final score amounts to 8.