Most people in Brazil (and probably elsewhere too), rely on seeing the axilliary feathers to clinch the ID of a single Pluvialis plover on the beach, black in Grey Plover and grey in American Golden Plover.
However, if the bird doesn't fly it is still possible to make a firm ID of the bird given good views. It is not good bird craft to cause a bird to fly just to ID it, especially if it is a migrant.
With a single bird, comparison of the bill is not easy, but this photo shows how much bulkier the bill of Grey Plover (right) is than American Golden. Also the more capped appearance of American Golden can be seen here as the supercilium in Grey is not so well defined.
American Golden Plover Pluvialis dominica (left) & Grey Plover Pluvialis squatarola © MZUSP |
Grey Plover Pluvialis squatarola |
American Golden Plover Pluvialis dominica |
Another anatomical difference can sometimes be hard to see in the field, especially if the birds are feeding in soft mud or sand. Grey Plover is the only Pluvialis plover to have a hind toe. It is very small but should be visible with good views.
Grey Plover Pluvialis squatarola © MZUSP |
American Golden Plover Pluvialis dominica © MZUSP |
Grey Plover Pluvialis squatarola 3 visible primaries © MZUSP |
American Golden Plover Pluvialis dominica 4 visible primaries © MZUSP |
The wing tips on American Golden Plover fall beyond the tail tip giving the bird a very pointed look to its back end. © MZUSP |
Grey Plover Pluvialis squatarola
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