Adult Thayer’s Gull-type (with Herring Gull characteristics?) – 20140216

While at the BP oil refinery at Whiting, Indiana on Sunday 15 February with Amar Ayyash, Matthew Winks, and Geoff Williamson, this gull was observed.

It was initially identified as an adult Thayer’s Gull Larus thayeri, but some were of the opinion that it showed some characteristics of Herring Gull Larus smithsonianus as well.

Characteristics that point towards Thayer’s Gull include:

  • Raspberry eye ring
  • Thayeri pattern on P10 and P9
  • Distinct pink legs

Characteristics that (potentially) point towards Herring Gull include:

  • Black markings on the inner web and outer web of P5, creating a ‘W’
  • Bill shape and size
  • Limited streaking on the head

This bird is being discussed on the Facebook page of the North American Gulls group and I’m posting my photos here to hopefully help in that discussion.

It might well be that this gull has to be left unidentified.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

16 February 2014, BP Whiting refinery, Indiana, USA.

BP Whiting refinery, Indiana, USA:

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