Hawks’ Winter Haven : Birds of Prey Flocking to Wildlife Refuge at Seal Beach Naval Station, Survey Finds

The bait was set. A small wire cage containing a mouse and a sparrow sat in a field, easily seen by any of the sharp-eyed red-tailed hawks in a nearby grove of eucalyptus trees.

Within 20 minutes, one of the large birds swooped in for a late breakfast and was snared.

An elated biologist, Pete Bloom, had one more startled young bird to measure, weigh and hold firmly, carefully avoiding its sharp talons, while he wrapped an aluminum identification band around its leg.

It was the 116th red-tailed hawk that Bloom had banded and the 221st he had counted so far this winter at the Seal Beach Naval Weapons Station.

Bloom, who is under contract with the Navy to identify and count all birds of prey that utilize the 5,000 acres of marsh and uplands, works even after sunset, searching the night sky and fields with spotlights for owls.

The survey is part of a joint effort by the U.S. Fish and Wildlife Service and the Navy to protect and enhance wildlife in the undeveloped part of the military facility.

Besides warehousing weapons, the site is an important winter destination and rest stop for southbound birds of prey along their historic migratory flight path between the Arctic Circle and South America.

In recent years, biologists have achieved a resurgence of endangered shorebird species at the station by controlling predators and providing a man-made island and floating nests.

They also want to increase the numbers of hawks, owls and other birds of prey that mostly hunt in the station’s expansive uplands that shoulder the marsh.

Off limits to the public and protected from development, Bloom said, the large expanse of open space at the station is “an incredibly significant resource that supports several species of raptors (birds of prey) that are almost absent in the rest of Orange County.”

And it is increasingly essential to migratory birds, he added, as other wetlands and open spaces fall to development along the western coast of North America.

“Birds that are migrating south along the Pacific Flyway have no safe place to land and catch a meal in the 30 miles between the Santa Monica Mountains and Seal Beach,” Bloom said.

“The most important aspect of the Seal Beach Naval Weapons Station is that it is protected and will remain a sanctuary.”

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One of his most surprising findings, Bloom said, is that the uplands provide a winter home to the highest density of red-tailed hawks in North America.

The booming population of red-tailed hawks, Bloom said, reflects an exceptional breeding year for the birds throughout California, Oregon and Washington.

The hawks, 90% of which were fledged last spring, are attracted to the base, he said, by an abundance of ground squirrels and gophers that inhabit the burrow-pocked fields and offer good eating.

Bloom said he has found 20 species of birds of prey on the base, including eight pairs of burrowing owls, a once common inhabitant of Orange County that has been nearly decimated outside the naval weapons station by development. “This is where they are making their last stand,” Bloom said of the owls.

In the winter, the base is visited by a growing number of peregrine falcons, a bird of prey on the federal and state endangered species lists. Bloom said he expects at least 100 migrating peregrines to stop at the base this winter to feast on smaller shorebirds.

The peregrine population is starting to rebound nationwide because of a reduction in the use of agricultural pesticides and because of efforts to breed captive birds, whose offspring recently have been released to the wild in large numbers, Bloom said.

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While birds of prey inhabit the uplands, the marsh is filled with shorebirds and water fowl, including large flocks of Canada geese that drop in this time of year to feed on dry lima beans left after the harvest on nearby fields that the Navy leases to farmers.

In all, 155 bird species use the station, said Rodd Kelsey, a biologist who works for the Navy and oversees protection of wildlife on the base. Among his challenges, he said, is dealing with barn owls that raise their young inside some of the partly vacant storage buildings.

Another of Kelsey’s responsibilities, he said, is making certain that those who farm on the base do not endanger the birds by using pesticides or exterminating rodents that the birds depend on for their diet.

Credit for a significant local comeback of two bird species, the California least tern and the light-footed clapper rail, both of which are listed as endangered, is given to the U.S. Fish and Wildlife Service, which since 1972 has operated about 1,000 acres of marshland on the base as a national wildlife refuge.

While the least tern population at the station dwindled to only five in 1983, Kelsey said, biologists last spring counted 198 pairs nesting on a man-made island surrounded by electric fencing to protect the terns’ eggs from opossums, skunks, hawks and other predators.

Michael Mitchell, a U.S. Fish and Wildlife Service biologist at the weapons station refuge, said that there has been an even more dramatic rebound of light-footed clapper rails, which over the last eight years have multiplied at the refuge from 10 birds to 150.

Artificial floating nests have been provided to encourage the birds to breed on the water, out of the reach of skunks and opossums.

But most importantly, Mitchell said, the U.S. Fish and Wildlife Service between 1986 and 1993 trapped and removed about 300 red foxes, a non-native species of fox with a wide-ranging appetite that had been thriving on the endangered birds at the weapons station.

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Bloom said the light-footed clapper rail is not the only bird to have benefited from the removal of most of the red foxes; so have hawks and other birds of prey that no longer have to compete with the foxes for rodents.

“It is an ecosystem coming back into order,” Bloom said.

If development plans for the Bolsa Chica wetlands south of the weapons station are implemented, Bloom said, all of the Bolsa Chica uplands that support birds of prey will be destroyed.

One result, he said, may be a further increase in the number of hawks in Seal Beach. “However, some of the red-tailed hawks would not survive the loss of their homes,” he warned.

As a result of his findings, Bloom said, he may recommend that the Navy plant at the station native trees such as sycamores that have natural cavities favored by owls and limbs that other predatory birds can use for roosting, hunting and nesting.