The tour boat puttering through the marshes cut its engines and beached on a sandbar. The hushed voice of Skimmer captain Ted Appell came over the loudspeaker. “Whooping cranes at nine o’clock,” he whispered. “No sudden movements, no yelling.” Silence reigned as twenty pairs of eyes focused on two big birds high-stepping through the grassy saltwater falts of Aransas Bay a hundred yards away.

Graceful creatures with long Audrey Hepburn necks, the cranes dipped toward the water to feast on crawfish, blue crabs, clams, and wolfberries. Their snowy-white bodies and black crowns topped by a crimson blaze — not to mention their nearly five-foot height — made them easy to spot. At the Aransas national Wildlife refuge, 35 miles north of Rockport, the last remaining wild flock of these rare birds eats its breakfast under the watchful eyes of a biologist (who regularly buzzes the flock in a small airplane in order to count them), boatloads of tourists, and tugboat crews pushing barges full of chemical fertilizer up the waterway.

Once abundant, whoopers almost went the way of the dodo in the early part of this century, as hunters slaughtered them by the hundreds in their wintering grounds in southern Louisiana and as their nesting grounds in Iowa and the Dakotas fell to development. Those factors, combined with egg collection, reduced the population to fewer than 15 in the late thirties. Since then, stringent conservation efforts — particularly the creation of the 54, 829-acre Aransas National Wildlife Refuge in 1937 — gradually reversed that trend, and in 1991 the whooping crane count reached 146.

This winter, though, the population fell. So far only 133 birds have completed the annual 2,600-mile trek to Texas from their summer nesting grounds at Wood Buffalo National Park, in northwest Canada. Aransas refuge biologist Tom Stehn attributed the decline to a regular ten-year dip in the population (this year’s came right on schedule) and run-ins with power lines (whoopers’ worst enemy). On top of that, a reduced flow of fresh water into Aransas Bay has put additional stress on the cranes, forcing them to leave the area to find drinking water several times a day and affecting blue crabs, a favorite food. Furthermore, thanks to a severe drought in Canada, only 9 chicks survived last summer. Avian tuberculosis and other diseases also took a toll, and a Marble Falls poacher named Billy Dale Inman was convicted of shooting a female crane last spring while it was migrating.

Meanwhile, back on the Skimmer, we found out in no uncertain terms how the whooping crane got its name. Suddenly one bird let out a deep, throaty noise that sounded like a gull squawk to the tenth power. Then it pointed its beat at the sun and took off, its black-tipped wings carrying it skyward like a C-135 cargo plane. A chorus of oohs and aahs arose from the boat’s passengers.

Whoopers may be viewed from the heron Flats hiking trail and the observation deck of the Aransas refuge — reached by car via Austwell — but the best perspectives, and the most fun, are provided by four tour boats that sail from Rockport. See the cranes while you can; they head back to Canada in April.