I had spent the morning watching the Durlston Red-eyed Vireo which showed erratically, but regularly in the field, after we saw it released. I left at lunchtime, to nip home for a quick lunch, before heading to Brands Bay for my 13:00 WeBS count.
Once the WeBS count was completed, I left for Portland Castle, where a Red-necked Grebe had been on view since it was found about Friday lunchtime. It should have been too far to travel for a Red-necked Grebe, but this individual has been suggested as potentially the American holbollii subspecies. Strictly, this is incorrect as it also occurs in North East Asia, including Mongolia, China, South Korea & Japan. The main range of the nominate subspecies is the Western Palearctic, but there are eBird records from as far East as Kazakhstan.
I didn't know much about the American subspecies, which is sometimes referred to as Holboell's Red-necked Grebe. A bit of digging on the internet revealed there are two accepted UK records:
- Gruinard Bay, Ross & Cromarty, shot (Sep 1925)
- Quendale Bay, Shetland (Feb 24). This individual washed up dead a few days later & was confirmed by analysis of biometrics and DNA of the specimen.
I also found this information from BBRC.
- Identification of holbollii is problematic. It may show on average more yellow on the bill in breeding plumage, but firm subspecific identification rests on biometrics, holbollii being larger than the nominate subspecies. Claims of holbollii should include biometric evidence or details from a ringed or marked bird.
The Portland Castle Red-necked Grebe looked bigger in the field, but to be fair there were no other species with it to make a judgement. So, my comment is based upon many days of checking this Autumn's Great Crested Grebes in Brands Bay at varying ranges, including similar ranges on some occasions. It certainly looks longer-billed than the Red-necked Grebes I've seen around Studland over the last nearly three decades. Additionally, there is clearly a lot more yellow on the bill.
Fortunately, there are some excellent photos of the Portland Red-necked Grebe from the local toggers, including Pete Coe. Perhaps it would be possible to blow one of those photos up and do some measurements on the bill which would help to confirm the identify. While it wouldn't be possible to measure the exact bill length, the ratio of the bill length to the eye, compared to the bill depth at the nostrils might be possible to calculate. This could be included in the record, if it ends up getting submitted to BBRC. I think it looks to be a good candidate for holbollii. But I also think it's unlikely to be accepted by BBRC, based upon their criteria stated above.
Whatever happens to this record, it was an interesting individual to see. If it is proven to be holbollii, then seeing two different American rarities on the same day in Dorset would be impressive, as Dorset is the poor cousin of Scillies, Cornwall & Devon for American vagrants. The other thought I had whilst writing this Blog Post, I better make an effort to get some reasonable photos of the next Red-necked Grebe that turns up at Studland.