Clinching the Pacific diver at Caolas beag

I'm not sure that it needed clinching, but I needed more views to be certain in my mind. The problem was, on Saturday I'd seen the Pacific diver and it was perfect. Small size, dark flanks, grey cheeks and small fine bill. It was so different to the accompanying black-throated divers that it looked more like a grebe than a diver. I was completely happy that I was watching a Pacific diver, though I didn't see the chin strap or the vent strap. 

However, then I went back on Sunday and saw what I thought at first was the same bird, but the jizz didn't seem right. Features that had looked so good on Saturday now looked uncertain or even wrong, and it was especially missing the grebe like appearance. Then it rolled onto it's side..... no vent strap. At this point I should say that I was watching the bird at 750m distance, so picking up on jizz is difficult as are small plumage details and things like bill size. But if it was a Pacific diver I should have been able to see the vent strap. 

Then there was a further complication which clouded my judgement. Up until this point everybody had told me that the Pacific diver was currently the only winter plumage diver in this area, and as if to confirm this, all of the black-throated divers I had seen so far were in summer plumage. I was still convinced that I had seen the correct bird on Saturday, but Sundays bird looked like a black-throated to me. Had I got it wrong on Saturday? Was I wrong on Sunday? Or where there actually two birds? I needed more views or I would forever doubt myself.

With a whale watching trip booked for this afternoon leaving me with a free morning, it seemed like a good opportunity to head back to Big Sand and make the most of the flat calm conditions to hopefully get better views of the Pacific diver. Instead of wasting time at the burn mouth near the campsite at Sands, which is simply too far away, I headed immediately along the rocky shore to a headland about a 1.5km to the north west and scanned from there. 

It took me a while to find the flock of 17 black-throated divers because they were close to the island well over 1.5km away, but soon they drifted my way. Almost immediately I spotted a winter plumage diver with them and excitedly took some video, but no matter how hard I tried, it still didn't seem right and after watching for a while I could only conclude that it was an adult winter black-throated. It just wasn't a Pacific diver.

Photo: Pacific diver. Note the rounded head shape,
small bill, grey cheeks & complete chin strap.

This was crushing and I was at the point of giving up, slightly depressed because this now left my Saturday sighting in tatters. I must have made a mistake, I was no longer convinced that I had seen the Pacific diver at any time, and frankly I was even beginning to doubt that there had ever been one at Caolas beag. After all, hadn't I been told that there was only one winter plumage diver here? I had one last scan over the sea.

Amazingly within a minute I picked up a second winter plumage diver and knew instantly that it was the Pacific. It's whole jizz was so different. It was a long way out, probably 1km, but it was with a summer plumage black-throated and the difference was stark. This was no indecisive "is it or isn't it?" moment, this was a slap-bang in the face "That's it!" moment. I did a little dance on the spot, but thankfully there was nobody to see, just a few bemused and slightly nervous sheep.

Photo: Pacific diver with black-throated. Note the
difference in head size & shape as well as bill size.

The two divers made their way slowly towards the larger group and eventually joined up with them and were now about 500m away from me. Apart from all of the other identification features I have so far mentioned, I could now also see the chin strap. This was more like it!

Best of all, I was thrilled to see that the impression I had got on Saturday was correct, this bird did indeed look like a grebe in amongst the divers. My photos even capture that impression perfectly, just as those taken by Tor Olson did of a bird in Norway in 2015, which I included in my post on Saturday.

But what type of grebe is it???

Finally it rolled onto it's side and preened, revealing it's vent strap! Perfect. Colin's finally happy that it's a Pacific diver. Hallelujah! Now we can all sleep easy.....