Eastern Olivaceous Warbler - Farlington Marsh 15th September

I was at the Romsey show on 14th when news broke of an Eastern Olivaceous Warbler at Farlington Marsh. I had consumed far too many ciders to even contemplate trying to see the bird on the day of discovery, not just from a driving perspective but through lack of an ability to focus. On 15th I awoke to the birds continued presence and, so after a bacon sandwich to soak up the residues of yesterdays over indulgence, I was on the road. Arriving at 11:30 the bird soon showed well as it fed in a stand of Goat Willow alongside Blackcap, Chiffchaff and a loan Garden Warbler (my first of the year!). Mostly the bird was flicking through the undergrowth but it would make occasional sallies to pursue flying insects and would occasionally sit motionless in the vegetation affording good views. At one point the bird headed very rapidly through the brambles heading southwards, we followed at some pace and eventually got better views as the bird fed in brambles and hawthorn before it headed back to its original location.

Eastern Olivaceous Warbler - Farlington Marsh, Hampshire

Eastern Olivaceous Warbler - Farlington Marsh, Hampshire

Eastern Olivaceous Warbler - Farlington Marsh, Hampshire

Eastern Olivaceous Warbler showing the full extent of its tail tip which helps to separate it from other similar species 

- Farlington Marsh, Hampshire

Eastern Olivaceous Warbler - Farlington Marsh, Hampshire

Eastern Olivaceous Warbler - Farlington Marsh, Hampshire

There are 21 accepted records of Eastern Olivaceous Warbler to the end of 2017, of these 14 have been from 2000 onwards. There have, unsurprisingly, been nine records from Shetland and three from the Isles of Scilly. The only south coast records have been from Dorset, all from Portland Bill in July 1999, August 2003 and May 2008 all of which were trapped. I have previously seen Eastern Olivaceous Warbler at Hoswick, mainland Shetland on 10th October 2013 (see below) and also in Cyprus, Kenya, Morocco, Yemen, Tanzania and Cameroon.

Eastern Olivaceous Warbler - Hoswick, Mainland Shetland 10th October 2013

Eastern Olivaceous Warbler - Hoswick, Mainland Shetland 10th October 2013

HBW Alive treat 'Eastern' Olivaceous Warbler as Olivaceous Warbler while 'Western' Olivaceous Warbler is Isabelline Warbler. HBW Alive list five subspecies that differ mainly in tone of colour and in size. The subspecies elaeica is the most likely to reach the UK and is largest, with the longest primary projection and darkest flight-feathers and tends to be greyer above than other subspecies with the most pronounced pale secondary panel in fresh plumage. Elaeica occurs from south-eastern Europe eastwards through the Caucasus to Xinjiang in north-west China. The subspecies winters in the central and eastern Sahel region of Africa.

The species was once considered conspecific with Western Olivaceous (Isabelline) Warbler, but recent work has confirmed substantial differences in mitochondrial DNA, song, behaviour and morphology. Western Olivaceous Warbler has not been recorded in the UK to date. An excellent ID paper to Western and Eastern Olivaceous, Booted and Sykes's Warbler can be viewed here.

Distribution map of Eastern Olivaceous Warbler - HBW Alive