On the 7th of December, David Álvarez, Luis Mario Arce and Elías García saw and photographed a juv "Black-throated" diver in the harbour of Santoña, N Spain. There were a couple more divers around, including a second Black-throated, so they quickly forgot about the first one.
Luckily, David posted one of the pictures of the first "black-throated" in his blog. Yesterday night I was reading his blog, when I came across that picture. I opened it, and inmediately thought: Oh my God, this looks a lot like a juv Pacific Diver!!
I asked David to send me more pics of the bird. He sent me three more, and it was obvious that the bird lacked any white on the flanks/thighs, even when relaxed. Scapulars looked really good too for Pacific, with well marked scaling, and the bill was also good. Nape was darker than expected, based on my limited experience with Pacific in California, and the bird lacked the typical chin strap found in most adults and some juvs. For those reasons, I decided to contact Killian Mullarney for expert opinion on the bird.
As usual, he kindly replied, almost instantly, saying the bird was, in his opinion, definitely a juv Pacific Diver! Considering some Pacific juvs can lack the chin strap, and that lighting conditions can affect the colour of the nape, he felt there was nothing wrong with the bird being a Pacific.

You can see some of the pictures of this first for Spain here:


and I´ve just uploaded one of them in the Europe stop press gallery.

A short note, with more pics, will be published soon

There are several birders looking for the bird now. Let´s hope it´s found again.
I´d like to thank Killian for his comments on the bird.

all the best

Daniel L. Velasco