Tuesday, 17 April 2018

Glaucoides to the left of me, Glaucoides to the right of me and a Black-necked Grebe in the middle of Aveley Pool

Arrived at the Stone Barges on the long walk to Rainham RSPB (14 Apr) with the knowledge that about an hour earlier an Iceland Gull was reported in the area. Presumably the bird of last weekend which had been seen during the week as well. Not many large gulls were on show so I started to walk down river. A few hundred yards east of the Stone Barges large gulls were beginning to gather in the middle of the Thames slowly drifting up river on the incoming tide. They had come off the landfill, typical behaviour, and also to be expected was that one minute there were a dozen present and then moments later a hundred dropped in. I scanned the flock and an immature Iceland Gull was drifting by. After a few minutes it flew to and landed on the Stone Barges jetty. Over the next few minutes another 'flotilla' of gulls had developed. A scan revealed another Iceland Gull in the mix, a whiter individual than the first with grey showing through on the closed wing. A quick look back at the jetty and the first bird was still present. I followed the floating Larids back to the Stone Barges where several other birders were scanning the gulls. As the paler bird drifted out of view, we then studied the original bird. It was tricky to see amongst the Herring and Great Black-backed Gulls on the jetty and best viewed from the right. Time went by and the paler Iceland Gull flew onto the jetty and all of a sudden one birder picked up a third bird, in plumage similar to the original bird. All 3 spent a fair amount of time roosting before the two 1st summer types flew off down river (one later drifted back up river and beyond the Stone Barges). The presumed second summer remained and then came to bread giving everyone a good look. Alos from the Stone Barges at least 3 Common Terns flew down river, my first of the season.

Several records shots of two of the birds below, check out some fine photos from Shaun Harvey of this gull at
Valley Birding.





How old were the Iceland Gulls? In the past the practice was to label as 1st winter then 1st summer and repeat the sequence through to adult plumage. A trend perhaps due to better understanding of moult patterns gave rise to calendar year labelling of birds, especially gulls, but can this always be applied?

On site at first I thought the second (paler) bird was a 3rd summer, but then wondered if it was an advanced 2nd summer. Looking at the literature still not 100% sure of its age, but I'm favouring 2nd summer if such terminology is still being used. The first bird looked like a typical 1st summer from my experiences, and I think the same of the third bird, although a little more advanced, it had a paler eye.

  • Bird 1 - dark eye and two-toned bill appearing black-tipped. Missing a primary on the left wing when seen in flight.
  • Bird 2 - strikingly white with grey saddle, not extensive grey but on closed wing in certain light looked to have grey on the wing. Pale eye and bill had a pale tip beyond the black band. Bill more yellow in tone than the others. Looked clean winged in flight.
  • Bird 3 - as Bird 1 in upperpart tone, eye appeared paler but not as striking as Bird 2. Hint of a pale tip developing on the bill. Missing primaries on both wings in flight.
Lots of good birds seen on the reserve that day. Whilst watching the passage Black-necked Grebe a Red Kite showed briefly in the distance over the Target Pools mid pm before heading fast to the south west. Lots of Buzzards moved through during the day helped by temperatures rising to the high teens and a southeasterly tail wind. I saw about 10 of the 30+ tallied, but my count may have included a few local birds. Marsh Harriers took to the skies and my first Hobby sighting of the year with one hawking insects over the Eurostar line. Swallows still thin on the ground (2), but I heard my first Willow Warbler and UK Lesser Whitethroat of the summer. The Great White Egret continued, still maintaining it's half a mile birder exclusion zone!






More photos of the Iceland Gulls at 'Latest UK Bird Photos'.

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