Because they are common and widespread, sometimes I take cormorants for granted. Then one day I found myself living on the San Francisco Bay, in temporary housing, and I witnessed some unique behavior.
In the Bay Area the double-crested cormorant is the prevalent species. They spend their day swimming and flying in search of fish, and can often be seen diving underwater for prey. They are excellent divers, and have webbed feet for fast underwater propulsion.
On my first day here, standing on the balcony overlooking the bay, I noticed a very large flock of cormorants down at the water. There were hundreds of the black sea birds, and they were synchronistically flying in the same direction. They swirled together in a great dance, slightly above the water’s surface.
Most of us have observed individual cormorants on land, spreading their wings, drying out. But this enormous flock all swooping together was new to me.
I had many other tasks to contend with, while we sort out the remains of our fire-damaged property, so I was soon off to something else. But throughout the week I continued to notice this phenomenon. I was seeing it almost every day, and always in the early morning.
Cormorants are colonial nesters, and at night they roost in large groups. From the balcony I noticed they have a favorite sea wall, where they congregate. When they take off in the morning, they often do so together.
Then I learned why they fly together: for better fishing.
Although they do not always flock in groups this large, when it does occur, they form a line. The line of birds, close to the water, follow the fish underwater and chase them. More cormorants opportunistically join the flock, sometimes thousands.
They often fly in a “V” shape and there is a hierarchy to the front line; sometimes there are hundreds, sometimes just a dozen. They surge and swoosh and make abrupt directional changes, always following the fish underwater.
If the fish escape the flying predators, the cormorants quickly disperse.
But if the cormorants are triumphant and succeed in snatching the fish, then there is much splashing.
I went down to the water one morning this week to photograph the big flocks. I didn’t find the huge flocks, but I watched thousands of cormorants heading out for a day of fishing.
And while I was photographing the cormorants, I spotted a sea lion. I was watching the sea lion, waiting for it to re-surface after a dive, when the most marvelous thing happened.
A whale surfaced right in front of me. It gave the characteristic sigh sound, of breathing air, and breached the water’s surface. I enjoyed one second of seeing the whale’s barnacled back, and then it disappeared. Based on the size and color, and since it is their migration time, I am quite certain it was a gray whale.
These are a few of the riches of Richardson Bay, a marine sanctuary on the northern edge of the San Francisco Bay. I’m going to be here for at least three months, and am looking forward to sharing more with you.
Photos by Athena Alexander unless otherwise noted