Rare Birds in Spain
Photos

The Pacific Divers at Santoña, Cantabria, on 7.12.2009

Photos by David Álvarez and Luis Mario ArceAntonio Jesús Hernández

Comments edited by Ricard Gutiérrez

Introduction 

On 7.12.2009 three observers (Luis Mario Arce, Elías García Sánchez y David Álvarez Fernández)visited Santoña marshes, Cantabria. Close to the pier, two divers were seen, one at close range and photos were taken and included in one of the authors, David Álvarez, blog here also here.

One of the photos, reproduced below, was published in the blog and there it stayed until another Cantabrican observer, member of the Spanish Rarities Committee Daniel López Velasco noticed something odd in the bird that recalled him Pacific Diver, a species he had seem some time ago. In a message to rarebirdspain list he notified the record to the whole community. It was a 1st for Spain and only a 4th for the WP.

As he posted to WestPalBirds listserv was: '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'.

Luis Mario Arce has sent to Rare Birds in Spain a couple more photos of the bird and also two photos of the '2nd Black-throated Diver' which looks different to the 1st Pacific perhaps due to light, with darker nape, more robust bill. However he thinks is a 2nd different Pacific Diver:

El segundo ejemplar es distinto del primero sin ninguna duda. Aparte de diferencias en el plumaje, que no son atribuibles a las condiciones en que se hizo la foto, cuando yo le fotografié, David estaba fotografiando al primero. Exactamente, yo me había quedado rezagado y apareció cerca de mí lo que entonces identificamos como un colimbo ártico. Miré hacia donde estaban David y Elías y vi que David estaba haciendo fotos. Cuando me acerqué a ellos le pregunté a qué hacía fotos y era al primer colimbo ártico. Es decir, que simultáneamente él estaba fotografiando a uno y yo, al otro.

All three authors agree bird no.2 was indeed a different Pacific seen simultaneously. Pacific Diver shows a paler nape than any Black-throated usually seen in Spain. Additional characters according to Pyle (2008) are the shape of the femoral tract, which is darker in Pacific, shape of head plumage and bill, chin and vent straps and measurements. The Santoña birds only shows a hint of chin strap though.

On 19-20.11.2009 a Pacific Diver was reported in Cornwall and remained while these being seen here. See a report here.

See a compilation of the photos of the birds below.

Photographs

Photos © David Álvarez and Luis Mario Arce

First bird

Photos above © Luis Mario Arce

Photos above © David Álvarez

2nd bird

Two photos above also Pacific Diver Gavia pacifica © Luis Mario Arce initially misedintifed as arctica (e.g. darker nape, but may be a light matter). Also photographed at Santoña on 7.12.2009. This bird (or another?) was calling and communicating with the other above so the authors consider it was another different pacifica.

Acknowledgements

Thanks to David Álvarez and Luis Mario Arce for kindly supplying the photographs that are in this page. And also thanks to Daniel López-Velasco who identified the bird.

Citation
Álvarez, D. & Arce, L.M. 2009. The Pacific Divers at Santoña, Cantabria, on 7.12.2009. Rare Birds in Spain. Retrieved from http://www.rarebirdspain.net/arbsf059.htm 

The Pacific Diver(s) at Santoña, Cantabria, on 7.12.2009

Summary:
Introduction
Photographs
Acknowledgements
Citation