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Goatfish tastiest treat for fairy terns


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POSTED: Friday, April 03, 2009

A Florida teacher e-mailed me recently offering to share a fairy tern picture he took while visiting Midway in 1983.

He was in the Navy at the time, stationed at Barbers Point. I never received the picture, but he did send me an abbreviation that made me laugh.

“;Midway is a paradise for bird watchers,”; he wrote. “;In Naval aviation we referred to them as B-One-R-D's.”;

It took me a while to get it. Now I'll never forget it.

Nor will I forget the answer to another reader's question about fairy terns. She sent me an excellent white-tern picture she took on Lusitana Street near the Queen's Medical Center.

The photo caught an adult in a tree feeding its fluff-ball of a chick a silvery fish.

“;Do you happen to know the name of this little fish lunch?”; the photographer asked.

It's a question seabird biologists wondered, too. From 1978 to 1980, researchers collected the stomach contents of 241 white terns from several atolls in what is now the Papahanaumokuakea Marine National Monument.

Of the entire volume of food, 88 percent was fish and 12 percent was squid. That's no surprise. I've often seen fairy terns carrying little fish crosswise in their beaks but have never see them carrying squid.

What did surprise me was the most common fish type that our terns catch: goatfish. This is one of the last species I would guess because I think of them as bottom fish. After reading about Hawaii's goatfish, however, it makes sense their fry would be common seabird prey.

Hawaii's waters host 10 goatfish species, two of those endemic. These reef fish are open-water spawners, releasing their eggs and sperm in the water and then leaving the rest to nature. Because the odds are low that any resulting offspring will survive to adulthood, the number of sex cells released is high. One adult female yellowstripe goatfish, or wekea, for instance, can release more than 300,000 eggs at a time.

The eggs float and if fertilized develop into little silvery fish. When dolphins, tunas and other big fish chase these and other prey to the surface, fairy terns often join other seabirds for a feast. (Hokule'a voyagers call these “;bird piles.”;)

White terns don't submerge, but rather pluck fish from the surface or catch them in midair as the fish jump. This kind of feeding is called air-dipping.

Terns do their best fishing when its windy because that's when they can best control their flight.

The silvery fish in fairy terns' bills look pretty much the same to me, but they are not. The researchers found in the terns' stomachs 40-odd fish species (some were too digested to identify) from 33 families. Running a close second to goatfish were flying fish, followed by squid, mahimahi and needlefish.

These charming seabirds have as many names as an octopus has arms. The bird's Hawaiian name is manu-o-Ku. Its scientific name: Gygis alba. Nickname in the literature I've not heard used: white noddy. Another nickname I've not heard used: sea swallow. Nickname I wish was used more: Tinkerbell. Official common name: white tern. Former official common name commonly used in Hawaii: fairy tern.

Fairy tern has always been my favorite name, but now it's got a close second. Since my Florida teacher's e-mail, I've been calling them B-1RDs.


Susan Scott can be reached at www.susanscott.net.