Ring-necked Duck

 

    Ring-necked Duck (Aythya collaris); 3 males + 1 female

On November 22 I mistakenly identified four distant ducks seen at the Laguna de Barlovento as Aythya fuligula (Tufted Duck). It was only on my following visit, on November 27, that I was able to correctly identify the birds as Ring-necked Duck (Aythya collaris).

Ring-necked Duck (Aythya collaris) showing diagnostic white ring around base of neck

In the photo above, the diagnostic white ring around the base of the neck of one of the birds can be appreciated, plus the greyish upper wing bar.

Ring-necked Duck (Aythya collaris) showing whitish "spurs" on flanks.

Another diagnostic feature of Aythya collaris is the so-called white spur on the flanks, visible in the above image. 

My reason for initially doubting that these ducks are Ring-necked (A. collaris) and not Tufted (A. fuligula) is the head shape, which seems too rounded. Perhaps this is due to the angle of vision from my elevated observation point, about 20 metres above the water surface.