When watching rare birds I often look at them in far more detail than common species. With the red-rumped swallow seen on 10th May I saw that the underwing was dark dusky black, noting that the underwing coverts did not contrast with the primaries and secondaries. This is not recorded in any of the identification guides, when the underwing coverts are described and illustrated as being pale buff, the same colour as the underparts. This was confusing me.
In order to look into this further, I have searched for photographs of the bird and found four taken by Steve Round. One, used on deeestuary, appears to show dark underwing coverts as I noted. Another, more distant view but from a lower viewpoint, shows pale underwing coverts as expected.
So what is the truth? The photographic evidence seems incontrovertible; the bird did have pale underwing coverts. I still cannot explain why I did not observe this, but take it as another example of the weakness of the statement ‘I saw it with my own eyes’.