WATSONVILLE - If you spot a large brown bird flying with two white-capped eagles, you're witnessing history.
A pair of bald eagles have produced a chick in Santa Cruz County, the first known successful breeding in decades.
The juvenile was hatched, reared and fledged from a nest tucked into the branches of a eucalyptus tree high above a slough west of Watsonville.
"(Bald eagles) are a very charismatic and dominant species in our minds," said biologist Gary Kittleson. "It's great to see them."
That bald eagles are here to see is attributable to a 15-year effort to reintroduce the species by the Ventana Wildlife Society.
Bald eagles were brought to near extinction in the lower 48 states before the 1972 banning of the pesticide DDT, which thinned eggshells and doomed hatching. By then, only 450 pairs were left in the U.S. outside of Alaska. By the 1980s, none lived in California south of Mount Shasta.
The Salinas-based wildlife group reared baby eagles taken from nests in Alaska and British Columbia, and between 1986 and 2000 released 70 juveniles at its Big Sur sanctuary.
The goal was to establish a self-sustaining population of four breeding pairs. As of 2012, the group had documented bald eagles occupying 26 territories in a range that extended from Marin to San Luis Obispo and the fledging of 33 wild birds.
Executive Director Kelly Sorenson said his group was one of several working toward the same aim across the country.
"There are now 12,000 bald eagle pairs in the lower 48," he said. "It's an amazing success story."
In Watsonville, the eagles were helped along by the evolution of a slough system from intermittent marshland to a series of shallow lakes with an abundant supply of carp and bigmouth bass, Kittleson said.
Osprey, another large fish-eating raptor, have successfully raised chicks near the slough in at least two of the past eight years, as well.
The changing nature of the sloughs, due in part to urban development that sends runoff from storms to collect in the shallow depressions rather than being absorbed into grasslands, has been a boon for fish, Kittleson said. But others, who thrived in the more seasonal wetlands, have been adversely affected.
"We're getting the birds, but we're seeing fewer red-legged frogs," he said.
Kittleson also said questions about the impact of past pesticide use on water quality and wildlife remain to be answered despite the recent eagle breeding.
Kittleson said drought might be pushing bald eagles north from drier areas in Monterey County.
Open space preservation likely contributed to their success this year. The Land Trust of Santa Cruz County has protected a large swath of land around the sloughs from development that might scare off breeding eagles, he said.
Two years ago, a pair of eagles, possibly the same two, tried nesting at busy Pinto Lake, but for unknown reasons did not breed successfully.
Though Kittleson generally stayed a quarter-mile to half-mile away from the current nest site, he said the eagles became agitated when he climbed from his truck and set up his tripod, swooping down and calling out. To protect the birds and landowners, Kittleson is not disclosing the exact location of the nest, which is on private property.
"Even our casual viewing or disturbance can really affect them," he said.
Kittleson, who's been studying the Watsonville slough system for 25 years, first spotted the bald eagle pair in December. By January, he said, they were adding to a large nest started the previous year. Then, on Valentine's Day, he saw them together for the last time. After that, one was always at the nest, caring first for the egg, then the chick, he said.
When the chick, which Kittleson tentatively identified as a female, first left the nest is unclear. Chicks hatch in about 35 days, and then spend several weeks in the nest being fed by parents before fledging.
On June 30, Kittleson spotted her sitting on a telephone pole. She was being harassed by blackbirds and kites, unhappy to see a large brown raptor in their territory. But her parents were nearby, keeping watch. She'll keep close to her parents as she masters flying and fishing, returning to the family nest to rest. But within a year, she'll be off on her own. She'll mature in about four years, gradually developing the distinctive white head.