Dolphin Watch
More than they could chew
By ANN WEAVER
Article published on Thursday, May 3, 2007
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| Photo by ANN WEAVER |
| This cormorant, named bald ravens by early scientists, struggles with prey that is bigger than it can handle. |
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Who hasn’t bitten off more than they can chew? With humans, this is symbolic, a metaphor for an overwhelming project. At sea, it’s not symbolic. It’s literal. Sometimes even littoral.
Biting off a bite-size piece of food, chewing and swallowing is so human that it’s strange to think that many marine animals cannot do this. Instead of biting off chewable chunks, they’re designed to catch food that’s sized for swallowing.
Some marine animals, like orca (killer whales) and sharks, can wrestle bite-size pieces off of prey. Though natural, the circumstances are difficult to watch.
Bottlenose dolphins are designed to catch food that’s sized for swallowing but they don’t always adhere to this. Another local grab-and-swallow species is the double crested cormorant, glossy black birds paddling around the seas or drying outspread wings on channel markers. Also known as shags for their crest of feathers, it’s bizarre that their scientific name, Phalacrocorax auritus, means bald raven in Latin.
Cormorants chase prey underwater, propelling themselves at speed with webbed feet, as deep as 45 meters. They dine on fish, eels and small snakes, the latter probably an easy swallow. Because they feed underwater, you only see feeding behavior when they’ve gotten a hold of prey they can’t actually eat: one that is too big. This unpleasant situation surfaced one pleasant April morning.
Gauzy clouds made the sky white rather than blue. The wind gained speed steadily. I edged through a no-wake zone, the wind prodding me sideways.
Ahead, a cormorant floated on the surface with its head in the water. At first I thought it was showering. Cormorants shower frequently during the mating season, which this was; the bird’s blush of breeding orange is there for everyone to see. Showering birds dip forward and gyrate their wings to spin up filmy fountains of water that rain back down on them.
Cormorants here are tremendously flighty. That is, they have a huge flight distance, which is the distance one animal will allow another to approach before it takes off. Normally you can’t get anywhere near them.
Surprisingly, this bird stayed where it was. It wasn’t showering. It’d snared a big toadfish, with which it was wholly preoccupied.
It kept dipping the fish in the water. With long hooked beaks, it presumably had a good grip on the food. Then it tried snapping its head. Either way, the toadfish was too big to swallow.
In all this, the meal never moved.
Closer inspection explained the permanent Piscean ennui and avian struggle. The bird had skewered the fish on its upper beak. The cormorant wasn’t trying to swallow this giant meal. It was trying to dislodge it.
By now, the wind and I got the boat through the causeway. I glanced back. The bird continued its struggle. Best of luck, buddy.
Some days later, three adult bottlenose dolphins appeared in the distance. They cut from a deep channel into shallow feeding grounds waters and began hunting. I pulled over. A dolphin, P swung by the boat and continued on. A second swung by, Ouch. I don’t know if dolphins have good manners. But swinging by behavior seems to be an acknowledgement (greeting?) of a familiar figure (me). A third fin slit past a distance away. Predictably, it was Fishlips.
Ouch and Fishlips had been consorting with P for weeks. But at the moment, they sought a mid-morning munch.
Ouch appeared at the shoreline of a mangrove island in less than 2 feet of water. Suddenly, his powerful peduncle (tailstock) slugged the water sideways, left, right, left as he launched after zigzagging prey. Fishlips was heading over when Ouch surfaced and snapped a giant meal, the 2-foot long fish in his mouth, over the water.
In a chaos of action, Ouch lunged over the surface again and again, smacking the fish on the water or slamming and retrieving it, sinking back into the water on his back with the giant in his mouth crosswise like you in a pool biting a foam baseball bat. The fish, its blinkless eyes staring and its wide mouth gasping for air, had the universal look of horror.
Like all dolphin dramas, everything stopped suddenly, from the surface at least. Finally, Ouch surfaced without the fish. He headed toward Fishlips and the two swam away side by side. P joined them. They fell into step and swam into nearby watery cul-de-sac.
A white thing bobbed at the surface. Still staring, it was the hapless head of Ouch’s giant fish. Did it mean a meal or something more symbolic?
May this maritime moral serve you the next time you’re skewered on more than you can chew. Take small chewable chunks in stride, even if it means careening and lunging. Best of luck.
Dr. Weaver studies wild dolphins under federal permit GA1088-1815, National Oceanic and Atmospheric Administration. Send her an e-mail at acweaver@tampabay.rr.com or visit www.dazzlingdolphins.com.
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Article published on Thursday, May 3, 2007
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