Monday, June 21, 2004
One good tern
I went down to the Bay to watch the sunset on the longest day of the year. The terns, little white sea birds with black caps, forked tails, thin wings and red beaks, were diving on some tiny bait fish. It was very energetic activity. They'd fly back and forth thirty or forty feet above the water, head down, looking for food. When they saw a fish they would pause, flutter and dive, beak first, wings back, dive-bomber style. I think they probably get their fish every time.
As the sun set lower and lower, the terns flew off one by one into the wind until there was only one tern left. The herring gulls coasted overhead; they too were heading into the wind. The cormorants flew past in threes and fours into the wind. The sun set, turning a a long string of cirrocumulus quotation marks iridescent.
One tern kept going back and forth looking for food. At forty feet terns have to see their prey. They're not playing statistical averages like a pelican. They have a small beak; they get one fish at a time, they have to dive accurately. On the average, if these terns are to live, they must gain more energy from each fish caught than they expend catching it.
This one last tern flew up and down the beach as long as I could see it. Before the sun set, it dove as often as the rest of them. As the sun set it would start a dive, then abort ten feet above the water. It would look, pause, flutter, tuck head down wings back and begin its dive, then spread its wings at the last minute and regain altitude. Then once again it would fly up and down the beach, up and down, up and down in the fading light. I don't think it dove more than once or twice after the sun went down. But it kept flying and looking as the light faded, for as long as I could see it.
I thought, "Fool. Give up and go home. Don't you know you're in a losing proposition?" But then I realized that I was seeing diversity. I didn't know if I was seeing stubbornness or metabolic disorder or compulsive behavior or some avian form of bravery. But I realized I was seeing the kind of behavior that might be maladaptive today but adaptive tomorrow. Or behavior that might be adaptive in a different context. Sooner or later that bird was probably going to die from its maladaptive behavior. But in so doing, it was sacrificing itself to ensure the future of its species. It was one good tern.
As the sun set lower and lower, the terns flew off one by one into the wind until there was only one tern left. The herring gulls coasted overhead; they too were heading into the wind. The cormorants flew past in threes and fours into the wind. The sun set, turning a a long string of cirrocumulus quotation marks iridescent.
One tern kept going back and forth looking for food. At forty feet terns have to see their prey. They're not playing statistical averages like a pelican. They have a small beak; they get one fish at a time, they have to dive accurately. On the average, if these terns are to live, they must gain more energy from each fish caught than they expend catching it.
This one last tern flew up and down the beach as long as I could see it. Before the sun set, it dove as often as the rest of them. As the sun set it would start a dive, then abort ten feet above the water. It would look, pause, flutter, tuck head down wings back and begin its dive, then spread its wings at the last minute and regain altitude. Then once again it would fly up and down the beach, up and down, up and down in the fading light. I don't think it dove more than once or twice after the sun went down. But it kept flying and looking as the light faded, for as long as I could see it.
I thought, "Fool. Give up and go home. Don't you know you're in a losing proposition?" But then I realized that I was seeing diversity. I didn't know if I was seeing stubbornness or metabolic disorder or compulsive behavior or some avian form of bravery. But I realized I was seeing the kind of behavior that might be maladaptive today but adaptive tomorrow. Or behavior that might be adaptive in a different context. Sooner or later that bird was probably going to die from its maladaptive behavior. But in so doing, it was sacrificing itself to ensure the future of its species. It was one good tern.
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