Elegant Tern (Thalasseus elegans) parent bringing a fish in his/her beak to her youngster on Morro Strand State Beach, Morro Bay, CA. This is an anchovy of around 10 cm.
This photo is not a sharp as the Fool Island Pigeon Guillemots, but the field characters of Pacific Sand Lance body and tail are distinctive enough for a positive ID. A rhino's exposed culmen is pretty close to that of pigeon guillemot (33 mm) which makes these three sand lance about the same size class (15-18 cm). I see one fish on the left side of bill (silver white belly forward) and two on the right side of the bill with their bellies touching. These sand lance would be a bit wiggly as the rhino flew by and you can get a little sense of that motion given that none of the fish are in the same position.
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.
The wonderful resolution of this photo allows a confident identification of a clupeid because you can see distinctive scales on the back and in fact a few rough spots were scales have popped out through the trauma of capture and transport. Although the head is completely out of view the elongate fusiform body with only modest tapering in the peduncle suggest it is probably a Pacific herring or sardine and not one of the threadfin herring or shad which are relatively deeper bodied and taper a bit more in the peduncle. Royal Tern exposed culmen run in the 63-65 mm range, so this fish is probably at least 13 cm long.
Review the original posting to get some great field marks regarding Elegant and Royal Terns. I have also seen Caspian Terns with the unusually red or red mottled legs as well.
This week last year a clupeid in southern California met its demise in the bill of a Caspian Tern. This clup has its mouth partially open which changes the shape of the head but given the resolution of the photo you can't zoom in to see the fluting of the telescoping mouth. The strongly forked clear tail, the apparent absence or in fact inconspicuousness of the rest of the fins, the size and position of the eye, and the blue gray hue of the top also support a clupeid, probably a sardine, maybe a herring. This particular fish would probably be around 14 cm long.
It appears in the original posting of this photo that it was a courtship feed. This site (Ballona Wetlands, Playa del Rey, CA) is about 20 miles as the tern flies to a breeding colony at Bolsa Chica, but Caspians have nested on dredge spoils in other parts of the greater LA region as well. Clupeids are rich in lipids for their body size, so this a great courtship offering.
The key field marks on this fish identifying it as probably a Topsmelt (Atherinops affinis) is the relatively flat back, larger and more stiffly opened tail, conspicuous pectoral fin, and the smaller pointed head. The general stiffness of the body and white silver belly, silver striped side and green bronze dorsal surface also fit with Atherinidae ID. The abdominal anal fin is a shadow in the bill of the Caspian Tern which would be another great field mark. Because the fish is not showing an hint of blue hue it is probably not a Jacksmelt (A. californiensis), but Grunion (Leuresthes tenuis) can not be eliminated (by me at least). One other notable question about this photo is the black line streaming from the bill that seems to originate from the fish's belly. I would estimate this fish at 14-15 cm.
