Any way you could contact the photographer, and ask?
Also, there is a large contingency of NW photographers on the Nature Photographers Network website. Here's their link -http://www.naturephotographers.net/enter.html
They also have some regional sub groups. Here's a link to the Pacific Northwest Regional club -http://www.naturephotographers.net/imagecritique/bbs.cgi?a=vf15&ns=1
Someone there should have the answer. It's an iconic image that is posted in their galleries on occasion.