By Peggy Butler, special to the Journal

Just this week while walking, we heard a desperate, high-pitched cry sounding over and over again. It seemed to be coming from Third Lagoon.

It was impossible to ignore the unmistakable sound of a bird alerting just about the entire world of a clear and present danger.

With our binoculars, we followed the persistent ruckus towards a small jutting of rocks just off shore. A black oystercatcher, with his long, spectacular neon beak, was poised on the rocky point. Below, on a smaller nearby rock surrounded by water, another oystercatcher sounded the alarm with a shrill.

This must be Mr. and Mrs. Oystercatcher protecting the nest. They likely have perfected the communication between couples for some time, as this species is committed to family values and they mate loyally for as long as 20 years.

Overhead, the sky appeared blue and calm. Then seemingly out of nowhere an immature bald eagle descended low over the rocks. With loud, operatically high-pitched squeals, one of the pair took flight and with apparent fearlessness pursued the eagle.

Oystercatchers normally fly at a fairly low elevation over the water, but this one followed the eagle high into the distance. Envision a small, very loud black siren chasing a large, gawky teenager eagle, winging it high and fast—I’m curious how eagle parents react to such behavior.

Black oystercatchers, along with being loyal mates, are excellent parents. Each nesting couple produces an average of three eggs per season. Unlike Chickadees, for instance, which become self-sufficient in only two or three weeks, oystercatcher parents must find little mollusks, husk them, and provide feasting for an entire year. Learning how to shell mollusks takes that long.

During the year of training, the soft four-and-a-half inch orange beak of the young ones gradually hardens into a powerful double-edged sword, a tool that can pry open the clutched shells of bivalves, perhaps even an oyster on a rare occasion — this is not at all common, however, and may not actually happen at all.

In reality, oystercatchers eat mussels, chitins, and limpets. With all the hunting, feeding, guarding, and chasing predators, how do they get any rest? Well, they rest only one leg at a time.

You can often see them resting just off shore on little rocky outcrops with a single pink leg posted on a rock, and the other one tucked up under a wing. Sometimes they also hide their head under the same wing—but only if a guard is posted. They will be in a little clique of four or five other bright black and orange oystercatchers.

You can see them in the rocks off Jakle’s Lagoon, on rocks below the bluff trail at American Camp, near Grandma’s cove, and you can often hear them squealing across the water in front of the Lime Kiln lighthouse trail.

They have an extremely high-pitched repetitive ‘wheeh-wheeh-wheeh!’ It’s an effective crime deterrent—just ask that teen-aged eagle.

— Peggy Butler and family enjoy the many sights of San Juan Island, migratory and native. Read Butler’s two-part series on out-of-state license plates in the Sept. 7 and Oct. 19, 2011, editions of the Journal, and her tribute to the parental ingenuity of the Oystercatcher, Nov. 30, 2011, edition; or online, at www.sanjuanjournal.com