Least Tern: Fishing Attempt

A least tern fledgling in flight. Photo credit: Emily Rice, Marine Corps Base Camp Pendleton

A least tern fledgling in flight. Photo credit: Emily Rice, Marine Corps Base Camp Pendleton

It was a brilliantly sunny day; the surf built in glassy waves that crashed with a roar and all but drowned our attempts to call data back and forth across the colony as we surveyed the beaches at Naval Base Coronado, searching for the few remaining California least tern nests that still remain on the beach. The vast majority of the tern eggs we have located this season have already hatched, and though mortality rates have been high this year, there has been a growing rank of fledgling birds (young birds that can now fly) to be found gathered just above the tideline as we walk out each morning.

Though capable of flight, these fledglings still rely heavily upon help from their parents when it comes to obtaining food, and I have often seen an adult swoop in to land briefly next to a chick or fledgling, appear to peck them quickly on the beak, and then fly off, a transfer of freshly-caught fish that is over in a matter of moments. What I had failed to see before, however, was a fledgling attempting to fish on its own, so when I came to the edge of the colony and chanced to see one clumsily dip into the waves and then fight to gain altitude in the face of an incoming breaker, I stopped to watch with delight.

The sight can only be described as comical. Adult terns hover for a moment above a sighted fish and then plunge in a steep and graceful dive headfirst into the surf, breaking the surface again in the blink of an eye, charging aloft to find another hapless target. This fledgling, by contrast, was attempting to dive feet-first. Repeatedly, I watched it appear to sight a fish, flapping determinedly as it fought to remain poised above it. Apparently lined up to its satisfaction, it would begin to drop, wings only halfway drawn in to its body, feet held out in front of it. Still 15 feet above the surface of the water, it would seem to panic—Oh no! Too fast!—and unfold its wings again to slow its descent. Hovering for another moment, once satisfied with its speed, pitch, roll, and yaw, it would tentatively draw its wings in toward its body, drop another few feet, then hastily unfold them to repeat the process. After three of these hurried corrections, it dropped into the water slowly and gently as a falling leaf. I can only imagine the fish was long gone and laughing by then.

The fledgling continued with this clumsy practice for some time, and I was taken by the ironic realization that I seemed to know how to be a tern better than it did. These birds develop so much in such a short period of time, though. When they hatch, their wings are hardly the length of my thumbnail, and in a matter of weeks they grow into birds that I can barely contain with both hands. This fledgling had already endured the constant threats of depredation, exposure, starvation, and human disturbance to reach this milestone. I can only hope that perhaps in a day or two, executing a proper dive will be just another lesson learned.

Claire Steele was a research associate with the San Diego Zoo Institute for Conservation Research.

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