Thursday, 23 October 2014

Late Willow Warbler

The light rain that had been forecast for this morning didn't look likely to amount to more than a few spit and spots so I went out early hoping to catch a few more thrushes. As I was putting the nets up I could hear the occasional 'tseep' of a Redwing passing overhead in the darkness along with the calls of Tawny Owls in the adjacent woodland.

As it came light there were a few Song Thrush and Redwing around but not as many as I had hoped for and I only caught 1 Redwing and 1 Song Thrush on the first net round. The presence of a female Sparrowhawk probably didn't help and it wasn't long before she found her way into one of the nets.

If looks could kill. Not the best pose but holding her cradled like a baby was the best way for me to get a photograph.
A little while later a few Goldcrests were calling as they moved through and as I approached the nets it looked like I had caught 4 of them. On getting a bit closer I could see one was actually a warbler and not a Goldcrest, and a Willow Warbler at that. Of all the warblers it could have been at this time of year Willow Warbler was just about the least expected. It was quite a pale bird with cold greyish tones and very little yellow and almost certainly belonged to the sub-species acredula. In fact given its appearance, the date and recent easterlies I would happily stick my neck out and say that it is an 'acredula' Willow Warbler.

'acredula' Willow Warbler 23/10/14.

The wing length of 62mm was indicative of it being a female and it was carrying a moderate amount of fat (score 3) and weighed 8.2g. At first glance I thought it was an adult that hadn't moulted because the primaries and tail were quite brown and similar in colour to those of adults in late summer just before they moult. However I quickly realised we are in late October and not late July and that if it was an unmoulted adult the primaries would be showing much more wear and abrasion by now, in fact they would look rather shattered. It was a first year bird (1Y) and the colour and wear of the wings and tail were consistent with that age given the late date.

T1, T2, T3 and T4 on the left side of the tail (right in picture) had been replaced.

1Y female Willow Warbler 23/10/14, the latest I have recorded locally by around 4 weeks.
There was very little in the way of visible migration and it didn't amount to much more than 16 Jackdaws, 28 Redwings, 3 Song Thrush, 6 Mistle Thrush, 3 Reed Buntings and 4 Yellowhammers although the Yellowhammers could have been local birds. A few finches were blogging about including 40+ Goldfinches, 7 Siskin and 5 Chaffinch but no Redpolls or Bramblings. As the morning progressed the number of birds caught tailed off fairly rapidly and the final ringing totals (retraps in brackets) were - Redwing 2, Song Thrush 2, Sparrowhawk 1, Goldcrest 12, Willow Warbler 1, and Coal Tit 1 (1).

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