Probably a silly question, but are there any pictures of this bird?
it's happened before, it'll happen again.
not much of a looky-likey though...
The finder should not feel too bad. Anyone can make a mistake.
Brian's point is an extremely important one and part of the problem. Bird identification is extremely vexing, complicated and challenging and there will always be occasions when even the most competent of individuals are caught out by a more commoner species. Making mistakes in birding is not to be frowned upon but to be taken in context and used to enhance our knowledge. From my point of view, I have a far higher opinion of an individual if he realises his or hers mistake and can reflect upon it, much better than carrying on a charade and making attempts at a two-bird theory or otherwise.
In the case of this adult Common Greenshank, it was an unfortunate mistake by one of Northamptonshire's premier bird finders and an outstandingly competent birder. As he has now realised, he should have waited to see the bird fly before placing the sighting in the public domain. He would have then quickly have realised that his bird was not a Greater Yellowlegs.
To be honest, I am utterly appalled by the garbage being thrown at this poor guy by individuals that do not know one jot about bird identification nor birding, and can type from the comfort of their desk (I am convinced few of these time-wasters actually do any physical birdwatching). Furthering on the blame game, was it not surprising that none of the first 200 to see the bird challenged the identification with any commitment (including myself). We should all go to rare bird events with an open mind, a notebook and a field guide - and perhaps a list of pertinent features enabling us to make a satisfactory and accurate identification. There were MANY signs that this Greater Yellowlegs was not all it was supposed to be but ALL were overlooked until of course it flew. In future, any potential claimants of this species in Britain would be wise to see its rump pattern before resorting to the mobile and thus save any embarassment at a later stage. Yes, the two species are very closely related and very similar in overall appearance but the two-toned bill, square-ended white rump patch, barred flanks, breast-sides and belly, foot projection and brighter yellow legs should be enough to make a firm id.
We are all responsible for falling into the same trap time and time again. If that little pager on your belt tells you that a certain bird is that species, for some reason your mind goes along with it even though certain discrepancies are staring you in the face. One should travel to each and every bird with an open mindset and armed with material enabling you to verify that initial identification.