There are three birds in this image! Two close crops of seagulls are used to suggest a snowy mountain range, while the sky and a third small bird are composited in to further suggest the large scale..
EXIF for the primary photo:
Sony a7iii + FE 100-400mm F4.5-5.6 GM OSS @ 262mm
1/1600s, f/9, ISO 800
(All three photos were taken with the a7iii and 100-400.)
One of the most interesting picture in the contest
Thanks! Once I was examining the feathers at 1:1 I couldn't not see it.