Pigeon Guillemot with Sand Lance at nest on Fool Island, Prince William Sound, Alaska

Pigeon Guillemot with Sand Lance at nest on Fool Island, originally uploaded by dan.cushing.

The pictures don't get much better than these and these very good pictures are fantastic in training the eye to see more in bad conditions or with fewer field marks. You can see the guillemot's lower bill under the right operculum of the sand lance.  This particular hold on a fish is also more particular to guillemots than most other bill loaders. The smooth scaleless skin of the sand lance with the dark to light contrast and blue black hues are quintessential field markings.  It also worth noting that the bright white belly is opaque and without any transluscence.  And finally the small and strongly forked tail could probably be enough to ID even a silhouette as a sand lance because none of the gunnel or priclebacks with this elongate form have such a tail. I'd estimate the fish size/s  around 5 to 6 culmen's length or 15-18 cm.