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Ocean Watch Susan Scott |
Food is scarce for birds
that winter on TernDuring my work in a wildlife refuge last fall, tens of thousands of big, brash birds surrounded me day and night. Red-footed boobies sat on my head, frigate birds plucked off my hat and albatrosses continually snapped warnings at me to back off.
Right in the middle of all this seabird bluster strolled a small number of golden plovers, or kolea. I loved the sight of those delicate shorebirds prancing among the beefy seabirds. It was like watching ballet dancers attend a "Smackdown!" show. It was also as risky.
One day, another biologist and I spotted a plover staggering on the beach. Before we could move, a frigate bird swooped down, snatched up the injured shorebird and flew off.
We were horrified. But that wasn't the worst of it. Young frigate birds hone their fishing and pirating skills by dropping and retrieving things. They also practice snatching items from each others' beaks.
And that's what happened to that poor plover. A gang of juvenile delinquent frigate birds turned that poor little kolea into a feathered frisbee.
Life is also hard for kolea in the food department.
Natural shorebird foods, such as native mollusks, crustaceans and insects, are often in short supply on tropical islands.
Our warm waters are nutrient poor, and many of our native insects are either absent, rare or extinct.
Here on Oahu, kolea feast on bugs, reptiles and other invertebrates introduced by people. Researchers speculate that because of this relatively newfound bounty, more plovers winter here now than ever before. This is one of the few cases where human alteration of the environment has helped a group of animals rather than hurt.
Tern Island also hosts alien geckoes, spiders and insects, but the tiny island's 36 acres can't hold enough individuals, native or alien, to feed the hundreds of shorebirds that land there each fall. Therefore, many of Tern's migratory birds starve to death.
I wrote plover expert Wally Johnson about an emaciated plover dying in my hand. He replied that the bird "was very likely a juvenile. ... Some of the 'kids' have a tough time on their first big trip."
Do they. One morning at Tern, I spotted a very skinny plover peeking nervously in the back door of the barracks. When I approached, the bird flew off.
I put a dish of meat scraps on the landing, and the bird, although still shy, began coming to the door each morning for a meal. It wasn't long before I had a pet, which we named Uncle Jimmy.
One day, I heard a commotion near Uncle Jimmy's dish and came out to find several ruddy turnstones after his hot dog. Jimmy fought like mad and drove the ruddies off.
After a couple of weeks, Jimmy stopped shying away when I came out with his breakfast. If he stood off, the turnstones acted like a tag team, some fighting the plover while others stole the food.
In the meantime a fairy tern laid an egg on a concrete block supporting our back door grill. A few days later, one of the biologists said, "Susan, Uncle Jimmy is totally out of control. He's beating up the barbecue tern."
My baby! The Rock!
The much-loved tern and its egg survived, but my housemates didn't like Jimmy much after that. I loved him even more. The scrappy kid had mastered the art of survival.
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Marine science writer Susan Scott can be reached at http://www.susanscott.net.