Sunday, 29 June 2014
Separating Baird's and White-rumped Sandpipers.
|Look how horribly similar these two birds are! If you look at the colour and pattern of the upperparts they are almost identical, the brown mask and brown cap also very similar. But if you look at the back end of the bird and flick your eyes from one to the other you can detect that the bird on the right looks so much more pointed; attenuated they call it in the books. Look more closely and you'll see why. The bird on the right is a White-rumped Sandpiper in breeding plumage and you can see that its wing tips are noticeably beyond the tail tip. The other bird is a Semipalmated Sandpiper in breeding plumage and its wingtips are more or less in line with the tail tip. The birds behind are Dunlins. Connecticut, USA 17/05/2012; Both photos Elis Simpson.|
White-rumped Sandpipers do not have white rumps! As you can see they have white uppertail coverts. We don't have a suitable photo showing a Baird's rump and uppertail but trust me, they do not have white rumps, uppertail coverts or anything remotely similar. If you see this feature, you can forget the rest of this blog. São Paulo, Brazil 25/11/2011.
Side by side you can see that the White-rumped Sandpiper on the right is greyer than the Baird's on the left, but alone this difference is too subtle to detect easily and bear in mind that the Baird's is in the clear Andean sunshine, while the White-rumped is on a beach in Brazil on an overcast day. If they had been taken in the same light the difference could well be even less marked. For interest the White-rumped Sandpiper is a juvenile bird moulting into its first non-breeding plumage. I has not moulted any of the coverts which it will keep until it moults again and it still retains one or two of the bright rufous scapulars from its attractive juvenile plumage. Baird's Sandpiper, Antofagasta, Chile 31/10/2013 - White-rumped Sandpiper; São Paulo, Brazil 24/10/2013
Here the flank markings can be seen on the White-rumped Sandpiper (right) quite clearly whilst the Baird's Sandpiper (left) has unmarked flanks. Baird's Sandpiper, Antofagasta, Chile 31/10/2013 - White-rumped Sandpiper; Rio Grande do Sul, Brazil 25/10/2013.
White-rumped Sandpiper (left) shows a less straight bill although the curvature on this one is rather exaggerated, the culmen (top edge of the bill) can often be as straight as the Baird's Sandpiper but it is not as finely tipped, is broader based and tapers more. It also shows the tell tale brown spot at the base of the lower mandible. Here too the feature of the feathering at the base of the bill can be seen quite clearly. Baird's Sandpiper, Antofagasta, Chile 31/10/2013 - White-rumped Sandpiper; Rio Grande do Sul, Brazil 25/10/2013. Both photos Elis Simpson.
In the above photo there is one of each of the species, taken in conditions in which you typically may well see them, not up close and in feather perfect detail in good light, but a little distant and in a gloomy overcast ambience. However, given everything we have said above, even though all the features are not visible, you should now be able to see enough to tell which is which here... Tierra del Fuego, Chile 06/11/2013.