Naval Nest : Station an Important Sanctuary for Birds of Prey

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 this season 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 skies 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 migratory flight path between the Arctic Circle and South America.

In recent years, biologists have aided 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 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 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.”

Bloom said one of his most surprising findings 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 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, Bloom said, by an abundance of ground squirrels and gophers that inhabit the burrow-pocked fields and offer good eating.

Bloom 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 decimated outside the Naval Weapons Station by development. “This is where they are making their last stand,” Bloom said.

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 list. This fall and winter Bloom expects that at least 100 peregrines will stop at the base on their winter migration 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 successful breeding efforts, Bloom said.

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

In all, 155 bird species use the Navy 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 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 by exterminating rodents that the birds depend on for their diet.

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

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

Michael Mitchell, a U.S. Fish and Wildlife Service biologist at the weapons station refuge, said 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.

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

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