Tuesday 17 April 2018

Hitting the Heights at Hinksey 16th April 2018

I was just setting off for Farmoor when a text alert arrived from Ian, our esteemed County Bird Recorder and was quickly followed by one from Badger. Both conveyed the startling news that there was a singing Iberian Chiffchaff at Hinksey Heights Golf Course which lies just southwest of Oxford and adjacent to the A34.

This was a 'drop everything and get there as fast as possible' alert as far as I was concerned for I had yet to see one in Oxfordshire, where it is a very rare bird indeed, the last one being seen in 2000 at Great Tew, which I missed. A county mega without a doubt and a national rarity to boot.

The Iberian Chiffchaff had been found yesterday afternoon by Justin, who, whilst waiting to collect his son from a party at the golf club, wandered around the scrubby area running down to the nearby A34, below the golf club car park, and heard an unfamiliar song coming from the trees. He recorded the song and sent it to Ian, suggesting it might be an Iberian Chiffchaff. At first Ian was unsure but then in the evening decided it was the genuine article, informed Justin and the  news went out the next morning.

I got to the golf club, a forty minute drive for me, sometime after ten thirty in the morning to find only Roger, another Oxonbirder, looking for the bird and standing on a track below a hedgerow of hawthorn that screened the golf club car park from a downward sloping area of rough grassland, scrub and golden studded willow or sallow trees. In the distance, from our elevated position you could even see the fabled dreaming spires of Oxford.

Roger told me the Iberian Chiffchaff had just been singing but there was now no sign as it had flown off a long way and out of sight, to where the ground sloped down to the A34. Apparently it had done this once before this morning and returned  but that was of little comfort in my immediate situation. I would just have to be patient and wait to see if it returned like last time.

Pete and Steve, two more local birders joined us and later so did Jeremy and Mick, as more Oxonbirders made their way here to see this county mega.

We all stood in a group hoping it would somehow materialise but it didn't. I wondered what to do and in the end followed a nature trail that led in the rough direction of where Roger had said it had flown but despite walking quite a long way I could hear or see nothing that remotely resembled the Iberian Chiffchaff and returned to find the others also at a loss, so we continued to wait but there was not a sight or sound of the Iberian Chiffchaff.

It was sheltered, even warm where we were standing out of the brisk cold wind, and the sun warmed me so much that I decided to discard my waterproof jacket back in the car and duly returned the short distance to the car park. Just as I got to the car I heard the distinctive and unmistakeable song of the Iberian Chiffchaff  coming from the other side of the hedge. Surely someone was playing a tape of its song but no, on checking through the hedge I could see the others below me on the track intently looking into a large willow tree. The Iberian Chiffchaff had returned. It was the real thing!

I immediately went from a state of resigned relaxation into one of high anxiety and it took but seconds for me to race round and down to the track to join the others and there was the non descript brown and white, small and unassuming leaf warbler that had brought us all here, belting out its surprisingly loud song, perched amongst the myriad golden dusted, green, thumb like flowers adorning the large willow tree.

Tiny and at times difficult to follow in the tree, it left us in no doubt about its continued presence, for it sang constantly as it moved through the whip thin branches hunting invertebrates and often moving to the very outside of the tree to briefly perch and sing. It was rarely still for more than thirty seconds, constantly on the move looking for prey and only stopping briefly to sing, before once more patrolling the tree for food.

It comprehensively searched each tree before moving to another, moving quite frequently from tree to tree but restricting its wanderings to the sloping area of scrub and trees below us and the smaller slope behind us. It rarely descended below head height and usually maintained a much higher position in whatever tree it favoured.

The differences between an Iberian Chiffchaff and our Common Chiffchaff are extremely subtle apart from their songs which are diagnostically different. The Iberian Chiffchaff's greenish brown upperparts and buff white underparts are a tad brighter than a Common Chiffchaff and the sides of the breast and under tail coverts can appear yellower while the supercilium is more prominent and can also show yellow in front of the eye. There was talk amongst us about wing formulas and primary projection but frankly these and the other plumage characteristics mentioned above are virtually impossible to discern or identify in the field with any confidence or authority and most, if not all Iberian Chiffchaffs are unidentifiable in the field unless they sing. That is the one  diagnostic feature that can allow  identification of an Iberian Chiffchaff in the field with any confidence.

Intriguingly we were also a little perturbed to  hear the Iberian Chiffchaff suddenly revert to the song of a Common Chiffchaff but only on a very few occasions and each time it did, it was for less than a minute. A paper published in British Birds explains that this can happen and why it is not a reason for immediately discounting the bird's credentials as being a genuine Iberian Chiffchaff.

Unfortunately the link to the British Birds paper does not work but if you Google 'Iberian Chiffchaff Identification' the relevant article should come up. It is entitled as follows:

'Identification of vagrant Iberian Chiffchaffs - pointers, pitfalls and problem birds' 
by J .Martin Collinson and Tim Melling

I remained looking at the Iberian Chiffchaff for over four hours and it became quite a social occasion as most of the birders coming to see the bird were local Oxonbirders. It was good to meet up with Phil after such a long time and to see him well and enjoying life whilst Mick, a recent arrival from Yorkshire, demonstrated that the traditional way of recording a bird by making field notes and drawings was not entirely redundant. Sometimes with everyone carrying a camera these days we forget how good, satisfying and thorough it is to make notes in the field and record our impressions instantly into notebooks

Hinksey Heights Golf Club could not have been more friendly and co-operative and willingly gave us free run of the area which was so refreshing compared to some experiences with golf clubs around the country that I have encountered. I joined Keith and Shirley in the 19th Hole for a pleasant lunch and then returned for another hour to continue looking at the Iberian Chiffchaff, but it was becoming slightly more elusive now, spending increasingly more of its time in some distant trees and only occasionally approaching as closely as it did in the morning.

It was time to go.

Update 20th April 2018

Sadly it looks like this potential addition to my list of species seen in Oxfordshire is not to be.The song and certain other biometric anomalies have sown an element of doubt about the exact identity of this very confusing bird. It appears to exhibit a mixture of Iberian Chiffchaff and Common Chiffchaff traits and as such is unlikely to be accepted as a bona fide Iberian Chiffchaff by the BBRC (British Birds Rarities Committee). Nevertheless it has been very instructive to study this bird which may never be assigned to either species due to the various anomalies.

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