Autumn Visitors Are Sights for Shore Eyes : Migratory Birds Rest, Then Fly On

From the boardwalk, a young boy surveyed the signs of fall at the Bolsa Chica wetlands. Small clusters of waterfowl--pintails, cinnamon teals, ruddy ducks--floated idly on the estuary, while groups of tiny Western sandpipers buzzed swiftly by, just above the water’s surface. But it was the majestic sight of a great blue heron--perhaps the most visible sign that migratory birds have arrived in the county--that caught the boy’s attention.

A short walk away, beyond the far end of the boardwalk, willets, marbled godwits, black-necked stilts and other shore birds roosted quietly, waiting for the tide to drop and expose the nearby mud flats, with their bounty of insect larvae and tiny crustaceans.

Uncannily Accurate Fliers

More than 75 people filed through Bolsa Chica on a recent morning, taking in the sights and sounds of autumn on the first of a series of annual tours offered by Amigos de Bolsa Chica. Fall has arrived, a time when bird watchers turn out in force at local woodlands and wetlands to enjoy the return of migrating birds from their breeding grounds to the north.

The accuracy of these fliers, some of whom stop in Orange County on journeys as long as 8,000 miles, can be uncanny: Western Sandpipers, tiny shore birds that can be seen in flocks of several thousand during migration, fly from their breeding grounds on the Arctic tundra to South America, often returning to “exactly the same place,” said Loren Hays, a Huntington Beach biologist who specializes in shore bird migration.

He told of two Western sandpipers that were caught together and banded by researchers in Peru one season--and returned, together, to the same spot the next season. “All these abilities are packed into 25 grams (slightly less than an ounce),” said Hays of the bird, which measures just 6 inches from beak to tip of tail.

The annual southbound trek of sanderlings and other avian travelers on the Pacific Flyway--an overhead pathway for migrating birds--marks the peak season for local bird watchers, who descend on favorite bird haunts hot on the trail of the county’s feathered visitors.

“Of all the months of the year, no matter where you go, October is the hottest month for birding in Orange County,” said Sylvia Ranney Gallagher, bird information chairman for the local Sea and Sage chapter of the National Audubon Society.

On a typical weekend morning in October, dozens of enthusiasts carrying binoculars and field guides can be spotted at such birding hot spots as the Bolsa Chica and Upper Newport Bay wetland areas, where migrating shore birds and waterfowl gather, or Huntington Central Park, a favorite place for finding the more elusive perching migrants, known collectively as “passerines.”

Bird watchers--or birders, as they call themselves--are a tight-knit fraternity. “Oftentimes we don’t even call each other on a Saturday, because we know we’ll run into each other somewhere,” Hays said.

Word Spreads by Phone

“There aren’t that many good places (to see birds) left in Orange County. They’re few and far between, so you’re likely to run into quite a few people.”

And when someone makes a rare or unusual sighting, word spreads quickly via telephone. “People come into the parking lot at Bolsa Chica with their tires squealing” after getting a call, said Vic Leipzig, a biology instructor at Coastline Community College and president of Amigos de Bolsa Chica, a volunteer group that seeks to protect the wetlands from development.

Although human development has taken its toll on county natural areas, Orange County has fared better than other Southern California coastal regions. Three relatively extensive coastal wetlands--Bolsa Chica, Upper Newport Bay and Anaheim Bay--are within a 15-mile stretch of county coastline.

“Areas like Upper Newport Bay . . . are hardly equaled along most of the Southern California coast,” said Kimball Garrett, ornithology collection manager for the Los Angeles County Museum of Natural History and co-author of “Birds of Southern California--Status and Distribution.”

Even so, Leipzig said, remaining salt marshes in Orange County and all along the coast “are just remnants” of former vast coastal wetlands systems. Bolsa Chica is one of the better preserved, at about 50% of its former acreage, but overall Southern California has lost about 90% of its coastal wetlands to development.

Such wetlands are crucial in providing migrating birds a much-needed refueling stop on their southward journeys. But, because of the draining and development of marshes, birds are finding these pit stops fewer and farther between.

“Wetland environments are certainly threatened in all parts of the world,” said Hays, “which is making the stopover points and refueling spots that remain all the more important.”

The productive salt marsh ecosystem provides a rich and varied diet for shore birds and waterfowl: algae, worms and insect larvae; crabs and small crustaceans; and clams, fish and the detritus of decaying plant material.

Up to 180 bird species have been spotted at Bolsa Chica during fall and winter; populations there can range as high as 10,000 for a single species--the Western sandpiper.

Some Spend the Winter

Some migrating birds stay for the winter, including many species of gull and waterfowl and some shore birds, such as marbled godwits and long-billed dowitchers. Others merely stop to feed and rest before resuming their journeys. In many shore bird species, some individuals will winter locally while others move farther south. In the case of the Western sandpiper, many of the males winter in Southern California, closer to the breeding grounds, while the females fly down to Central and South America.

Although a few individuals of many migrating bird species can be seen all year (mostly immature, non-breeding birds who have no need to migrate), summer bird populations are greatly multiplied in October with the combination of migrants that stay for the winter and those just passing through.

The numbers swell once more in spring as the migrants pass through again, this time heading north to breed. But, Gallagher pointed out, many of the young birds seen moving south through Orange County in autumn don’t survive to make the return trip north in spring.

Although shore birds, sea birds and waterfowl are relatively easy to spot at their favorite county haunts, migrating land birds such as warblers, flycatchers and vireos can be more elusive. “Passerines are harder to see in general, because they don’t parade around on the mud flats,” Hays said.

Parks Are Magnets

As they fly south over the coast, passerines seek wooded areas for feeding and resting. Areas such as Huntington Central Park in Huntington Beach, with its stands of native trees, are called bird “traps,” because they prove an irresistible attraction to migrating birds.

“Even though Orange County is largely paved over with houses, the few well-placed parks that exist tend to be magnets for migrating land birds,” Garrett said.

Migration itself is incredibly complex. “Migrating birds tend to follow fairly regular north-south corridors” such as coasts or mountain ranges, Garrett said, but he added that models such as the Pacific Flyway are simplifications. Flight paths and lengths, and time of migration, vary widely from species to species, and sometimes even within species.

Moreover, the inner mechanisms that birds rely upon to navigate the long distances--often flying at night--are not completely understood.

The variety and mysteries of migration are part of the draw to biologists and veteran birders, who often visit the same areas season after season. “That’s what makes it so fascinating,” Hays said. “It’s endlessly complicated.”