Posted on: June 29, 2014
Author: Rick Simpson
Report by Wader Quest
If, like us, you’ve always thought that telling a Baird’s from a White-rumped Sandpiper was nigh on impossible and only for the experts, then this blog may help you. Although we haven’t seen these species in all plumages (notably not juvenile Baird’s), we think that now we have cobbled together enough experience and knowledge to tell the difference, so, here’s how we do it.
I suppose the first thing to establish is that the bird is definitely either one or other of these two species. That first step is thankfully fairly straight forward. The clincher here is the wing length. In both these species the folded wing projects beyond the tail tip giving them a long pointed sort of appearance rather then the more blunt rounded back ends of most other similar Calidris waders.
So, we have seen the projecting wing tips so we know we have a Baird’s/White-rumped to deal with. Naturally we do not encourage anyone to flush a feeding or roosting bird to make it fly, but if your bird does fly or preen itself conveniently, as one did for us at Cley on the first day of Wader Quest back in 2012, then you will not find it hard to spot the white uppertail coverts on the White-rumped Sandpiper, or, if your bird is a Baird’s, that this feature is absent.
As conscientious birders you will not want to disturb the bird and the other birds around it, so you may have to make your identification based on other features. A lot of books talk about the Baird’s being browner, but if you have a single bird, comparisons of this nature are useless, especially as tones and colours depend so much on light condition.
So what do we look for? Well we often start with looking at the flanks of the bird. In Baird’s it will normally be clear white, whereas on White-rumped you will usually be able to detect some dusky streaks. Although Baird’s will sometimes show one or two fine feather shaft-streaks high up on the rear of the flanks; there is one on this bird.
A further pointer is the bill. That of the Baird’s is straighter and finer than White-rumped’s with a narrower tip. If you can compare the two it is fairly obvious, but again a lone bird may not be so easy and there is some degree of individual variation, however you may find another useful feature often apparent on the bill of White-rumped Sandpiper, is a brownish patch at the base of the lower mandible. There is also a feature that I have not seen written anywhere, but looking at the base of the bill where the feathers end, on the lower mandible of Baird’s Sandpiper it seems to extend much further forward along the bill then on the upper mandible; on White-rumped, although the lower feathering is further forward it is much less markedly so. Looking at many photos on the internet and in books, although this is not absolutely diagnostic in all individuals and the angle the bird is seen at can make a difference, it does seem to hold true in general. I would described the detail in Baird’s as looking like the profile of a person whose bottom lip protrudes slightly.
Call is often cited as a distinguishing mark too, but to be honest with you, the chances of hearing one call on its own, in isolation, in the general hubbub and din of a marsh and its denizens, or over the crashing waves on a beach, without actually disturbing the bird, are small. I’m not sure about you, but I’m not confident I’d be able to tell them apart in isolation anyway. Listening to the two one after the other on xeno canto it is possible to hear that the calls of the White-rumped are more squeaky, high pitched and, I think mouse-like, and those of Baird’s more bubbly and liquid in tone, but to hear one on its own? I know my personal limitations and I would not be happy if I couldn’t see a visual identification feature.
The scientific name of White-rumped Sandpiper is Calidris fuscicollis, the fuscicollis part of the name means dusky necked. Look now at the bird on the right in the picture and this will give you another good indication, where a comparison is available, of the difference. So, given all the above, although this is not the full story, it should give you some easy ways to at least have a confident stab at what you are looking at.
If you identified the birds above as Baird’s on the left and White-rumped in the right you’d be spot on. See? It’s not that hard after all… is it?