All this talk of America reminded me of a recent near miss I had whilst birding. I've never been to the USA birding, and don't tend to do much twitching these days, so subsequently I don't have much experience of many US Species.
However, on finding myself in the Orkneys recently in the face of very strong, very prolonged North West gales, I figured I had a better than usual chance of seeing something of American origin. So amongst other things, every Golden Plover flock was scanned for one with dark underwings. All were pure white as you'd expect, until in one small flock, I saw a dark underwing and axillary just prior to them landing. I soon saw "the bird" on the ground.. It had a fairly obvious white supercilium, and looked "perhaps" more black and white on it's back compared to the European Golden Plovers. However, the wingtips didn't go beyond the tail. So I followed the bird in my scope for about 45 minutes, not really getting any closer to confirming what I was looking at!
Eventually, and without any prompting from myself (although in the freezing wind I was tempted to induce this!) the flock took flight to reveal underwings.. all 100% pure white!
My initial reaction was unprintable.. I then picked up my tripod and walked away feeling quite gutted. A trick of the light combined with a bird with a slightly more strongly marked head had raised my hopes, and it took 50 minutes in freezing cold to realise I was just looking at my 500th European Golden Plover of the day! However, looking back that evening, I felt quite pleased that despite the initial evidence, the appalling conditions, and the barely contained excitement turning to disappointment, I did (eventually) reach the right conclusion, and left the scene with the correct ID.
I began to realised that many of my "not so good" days in the field were actually not as bad as they could have been! If days are ranked:
Best Day - 1st: Finding something unusual
2nd: Twitching something unusual
3rd: Not seeing anything unusual
4th: Realising you have walked past something unusual without picking up on it!
Worst Day - 5th: Getting the ID wrong!
Most of my uneventful / not so good days are a"3", with the odd "4"! (4's" are ok, as they at least prove I was in the right place at the right time, giving myself a chance of finding something good.) Touch wood I haven't had any 5's for many years! Instead, I have a few 99% certainties that aren't on my self found list when they were.. well.. 99% certain!
The experience reminded me of the December 6th 2007, and October 30th 2007 entries of David Sibley's excellent blog:- http://sibleyguides.blogspot.com/search?updated-max=2007-12-31T16%3A45%3A00-05%3A00&max-results=20 A really good read! A more recent entry with the "awareness test" is also an eye-opener! | 
