Monday, 31 August 2009

Farmoor Tern Extravaganza

Around about lunch time on Friday 28th August the word was put out that a juvenile white-winged black tern was on Farmoor. Needing no further prompting I set off there post haste and on arrival I soon met up with dedicated Oxon birder Phil Barnett. At the top of the car park embankment we had a good scan around Farmoor II and having picked out the bird at the far end we decided to walk along the causeway to get a closer view. At this point the heavens opened so we beat a hasty retreat to the hide at the top of the reservoir where we met up with Alan Brampton the finder of the bird as well as another county birder. We had just found it in the company of one adult and two juvenile black terns when they all four flew over to Farmoor I and settled on the barley bales in the middle of the reservoir. We therefore trooped back along the causeway where I was just about to take a digiscoped shot when they all set off again. We watched from the causeway for a while as all four birds hunted in the middle of Farmoor II before noticing that a fifth bird had arrived. I set off to go home at this point pleased with another county year tick.

Early evening, word was put out by Ian Lewington that the fifth tern that had arrived was in fact a great rarity in the form of an American black-tern. Apparently Ian had taken some video of the white-winged black tern and had noticed another tern that was in shot for some of the time which wasn't a usual European black tern. Having done all the checks he was confident in identifying it as an American tern. I spoke to a fellow county lister and we decided that it would be a good idea to nip back to the reservoir to have a look for ourselves. The reason was partly that whilst we'd both seen all five terns and therefore the ABT we hadn't actually picked it out in situ. We both admitted that we weren't going to deny ourselves the tick should we not see it again but that it would feel better if we could actually pick it out. It was virtually dark by the time we arrived and raced around to the Lower Whitely Farm end in order to be as fast as possible. We raced up the embankment and soon were watching all five terns. We were just able to pick out the adult black tern and the WWBT and it was possible to make out that of the three remainging juveniles one was definitely darker along the flanks. As it got darker, three of the terns flew progressively higher and higher until they were lost from view though we weren't able to tell which three they were.

The next day found the WWBT and ABT still present on the reservoir so it had obviously been the three EBT's that had left that evening. Fortunately these two remaining birds seemed quite pally and have stuck around since, being joined fairly quickly by another juvenile European black tern making a wonderful trio of terns and offering great comparisons between them all.

I chose to go back on the very windy and overcast Sunday in order to try and take some digiscoped photos. Conditions were pretty terrible which explains the poor quality of my personal record shots.

The juvenile American Black-tern on the left and the juvenile White-winged Black-tern on the right in this poor quality digiscoped videograb.

Here is the video footage from which the grab was taken, again the quality is very poor.

For the best photographs that you're ever likely to see of these birds it's worth looking at Nic Hallams Farmoor Birding web-site.

Oxon County Year List 2009
The white-winged black tern is a county year (and county life) tick for me though I saw the adult bird at Staines reservoir earlier in the year so it's not a national year tick. The American black tern is currently classified as a sub-species of the black tern: Chlidonias niger surinamensis and so is not technically a tick though it's apparently ripe for a split soon so an armchair tick could well be in the offing. Even so it's the rarest bird that I've ever seen in the UK with only a couple of previous sightings in this country with a couple more in Ireland.

173 White-winged black tern 28/08/2009 Farmoor Reservoir (County Lifer)

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