The Cormorant Show
Nothing amuses egrets more than watching Pelagic Cormorants. The shoreline game that I recorded earlier, involving just two Snowy Egrets, later expanded to draw five snowies plus one Great Egret, all hopping along the shoreline to keep up with the diving birds, and watching with as much fascination as humans at a circus. There wasn’t any obvious feeding benefit for the egrets, and there weren’t any hostilities. It just looked like a show that the cormorants were putting on and the egrets loved to watch.
Pelagic Cormorants, the star performers here, play only minor roles compared to their larger cousins, the Double-crested Cormorants. Out on the breakwater on the west side of the park, you can sometimes see many dozens of Double-crested Cormorants occupying 80 percent of the structure, with just two or three Pelagic Cormorants off by themselves on the outer reaches. See “Big Gulp,” Sep 14 2022. The two species don’t fight but they don’t socialize, either. The Double-crested frequently form packs of ten, twenty or even more birds that hunt together out in the middle or the North Basin. See for example, “Cormorant Commandos,” Sep 10 2021. The Pelagic Cormorant is much less social. Typically I see only one. Seeing two working together is noteworthy. Three as a team, as in the video above, is already special.
The Pelagic is capable of diving down 300 feet, but that’s a lot of effort. It prefers to work in shallow water over rocks where, in the cracks, edibles may be taking refuge. In the video you can see that they occasionally have success. They eat fish and any other marine protein they can catch.
Researchers have found them associating with other species in a given habitat, but I’ve not yet found mention of affinity with egrets, nor have I found mention of egrets who love to watch Pelagic Cormorants. If you have seen or heard this behavior reported elsewhere please post a comment. Thank you.
To distinguish Pelagic and Double-crested Cormorants by their looks, see “Two Cormorants,” May 15 2022. The Double-crested can also appear solo or in pairs. Telling them apart from Pelagic is easy once you know to look at the color on the base of the beak and the throat, as well as the shape and slenderness of the beak.
Burrowing Owl Update:
No Burrowing Owl seen anywhere in Cesar Chavez Park this morning. This is the second owl-less day. There is a possibility that “our” owl has relocated to the Albany Bulb Burrowing Owl Mitigation Area. A friend reports that two Burrowing Owls are present there today. If someone can get good full-frontal photos of the Albany Bulb owls we may be able to determine if one of them is “our” owl.
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Around 3pm today the owl was seen by someone with a scope at the usual north basin spot but it flew a little north
“… all hopping along the shoreline to keep up with the diving birds, and watching with as much fascination as humans at a circus. There wasn’t any obvious feeding benefit for the egrets, ….”
My interpretation is that the egrets are watching the water –for potential food to pick off.
The herons/egret are positioning themselves close to the edge of the water, or actually in the water, and are keeping up with the cormorants pace along the shoreline because that will position them closest to any prey directed their way –shoreward– by the diving cormorants.
I.e., the herons/egret are positioning themselves within ‘stabbing’ /’grabbing’ distance of any fish or crustaceans that might get stirred up and directed towards them.
But it does appear that they’re not getting a food in this instance.