How can I tell the difference between the female Greater Scaup and the female Lesser Scaup ? (1 Viewer)

[Xelioszzapporro!!]

Another duck identification question. This time I want to find out how can I differentiate the Greater Scaup (Aythya Marila) with the Lesser Scaup (Aythya Affinis)
Can't really tell them apart yet , .can you help me fellas ?

@Bewick @aeshna5 @Joern Lehmhus @jurek @smiths @nartreb @Southern Viking @Stephen Dunstan

This is Aythya Marila the Greater Scaup pair, the brown duck is the female





And this is Aythya Affinis the Lesser Scaup , once again the brown one is the female.

 

[THE_FERN]

Head shape for starters

 

[Southern Viking]

Yeah Greater has more rounded head, slightly broader body and head, finer vermiculations above in the male etc. Females tend to have slightly more white around the bill, especially above it (not always). If they flap their wings, the wing bar on Greater is all white, and on Lesser the secondary bit is white and the primary bar grey.

They can be quite tricky at a distance in situations where the head shape may be affacted by whether it's just dived for example. Wingbar is probably the best clincher if you can get it

 

[TheBlackGrouse]

When in doubt, size!

The Lesser Scaup has the appearance and size of a Tufted Duck. Often, in the Netherlands, these ducks are in groups with different species and then you can compare them.

 

[Xelioszzapporro!!]

Thanx fellas! You provided helpful and informative points. The head-shape and the more whitish face of the female Aythya Marila helps to differentiate the 2 species.