Actitis sp., Las Salinas Sep 19
The dilemma is obviously whether this Actitis species is a Common (hypoleucos), or a Spotted (macularius) Sandpiper.
The first conspicuous feature which drew my attention to this visiting wader was the very short projection of the tail beyond the primaries: it looks too short for the typical Common Sandpiper (A. hypoleucos).
On the other hand, there do seem to be dark notches along the edges of the tertials, just discernible in some of the photos, which would indicate Common (hypoleucos), rather than Spotted (macularius).
Although the notches are faint, they seem to extend along the feather edges, rather than being confined to their tips.
The strikingly short tail projection beyond the folded wings can be appreciated above.
In the poor quality image above, the wing stretching seems to show that the white wing bar does not reach the bird's body, a diagnostic feature of Spotted Sandpiper (A. macularius).
Actitis sp. Las Salinas, Sep 22
Regarding the bill, I can see no sign of a pinkish lower mandible, as in macularius.
The white underparts lack spots, of course, but what about those tiny dark flecks towards the bird's rear end? Dirt?
So far, I have not heard any vocalisations: the two Actitis species can be separted by their distinct calls.
It would also be useful to have some clear pictures of the bird in flight, to enable closer assessment of the upper wing bar. However, photographing this speedy sandpiper on the wing is tricky in its present surroundings.
For the moment, I am inclined to opt for Common Sandpiper (Actitis hypoleucos), mainly because of the dark (albeit faint) notching on the tertial edges, the pale legs, and the lack of pink on the lower mandible.
But the short tail projection, the stocky body shape, and the upper wing bar (visible in the blurred shot above) have left me with certain doubts.
Any comments or second opinions would be most welcome.