Farmoor Reservoir Bonaparte’s Gull

I popped into Farmoor Reservoir this morning, with no hope of more than the off-chance of a passing Osprey. I wasn’t early enough however, Geoff Wyatt had seen one pass through before I had arrived. I had just passed the first Cormorant, a cracking summer plumaged bird, with more nearly as much white on his head as I have….

… when I spotted Dave Doherty on the causeway. He had the manner of a man who had just found a good bird: ‘scope locked onto one area, whilst speaking animatedly into his phone. I scanned the water in front of him and immediately found the reason why. Even at distance, I could see that the bird on the far left of the jetty was a Bonaparte’s Gull:

This bird was found last week by Tom Wickens, but has not been seen since Thursday, some four days previously. It had the good manners to stand quietly next to an adult and first summer Black-headed Gull for comparison:

Occasionally it turned around to show off its other side…

… or to stretch a wing:

Then, two fisherman approached and walked onto the jetty and started up a boat. The Bonaparte’s Gull took flight, revealing the long thin dark line running along all the tips of the primaries and secondaries. The tail feather just left of centre is a white adult-type feather, contrasting with the neat dark terminal band on the other juvenile tail feathers. This feature may help this bird be identified elsewhere, if it is seen sometime soon.

As there were a couple of 1st summer Black-headed Gulls flying around, I took the opportunity to compare their upper-wing patterns. I cut and pasted the upper-wing pattern from the two photos below, then re-arranged them for comparison. The effect is not perfect, but the key features come through:

Apart from this North American visitor, there was a nice feel of migration in action at the reservoir. Swarms of Sand Martins buzzed about, with a few Swallows and my first Swifts of the year. Pied, White and Yellow Wagtails were passing through, joining small numbers of the commoner waders. A female Goosander looked a bit late.

And then from the sublime, things moved to the ridiculous…

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