Western Gull off Mexico?

[Eric Hopton]

Seen off the Pacicfic coast of southern Mexico, this gull is still puzzling me. I only managed to get this single poor shot.
I lean towards Western but clearly Californian is also possible. The wings were very dark with pale primaries but the heavily marked tail with dark terminal band shows up in the photo.

Any ideas would be greatly appreciated.

[Eric Hopton]

I meant to include smithsonianus as a possible and on reflection the location and extensive pale mirrors make this perhaps the most likely - it was a little too far south for regular Western.

[Chris Gibbins]

Hi. It is a skua rather than a gull....

Best regards

Chris