The distorted bishop pine stood out like no other within a narrow canyon full of evergreen trees on northern Santa Cruz Island. The top of it was mushroom shaped, crowned with sun-bleached sticks and branches woven into a sturdy nest eight feet in diameter, its center padded down with dried grasses, twigs, and discarded fish bones.
Scaling the tattered pine was tree climber Jim Spickler, methodically maneuvering 45 feet above ground, an anxious bald eagle chick peering down at him. The chick was eight weeks old, ready for banding and blood drawing, but another month away from its first attempt at flying. As Spickler drew closer, it appeared as if the eaglet was ready to fly right then, inching to the perimeter of its nest, wings flapping furiously. Spickler waited for the eaglet to calm down, and then lunged for a talon. Before the eaglet knew it, Spickler was cradling it in his arms while biologists from the Institute for Wildlife Studies (IWS) waited below to prepare this fledgling for life on the Channel Islands National Park.
It’s been more than 50 years and the National Park Service and IWS are just seeing the successful natural reproduction by bald eagles on the northern chain. During the mid 20th century, substances like DDT and PCBs were dumped by the tons by the Montrose Chemical Corporation into the Southern California Bight near Catalina Island, 60 miles south of the national park. Still prevalent off the islet today, bald eagles can’t incubate their own eggs for a full term without the assistance of biologists, although two eaglets hatched successfully on their own this past spring for the first time in 20 years since the Catalina restoration project began. In December 2000, Montrose was forced to pay $140 million with $38 million going toward restoring natural resources such as the bald eagle.
DDT is a chemical that bioaccumulates and is very slow to break down. Animals like the bald eagle at the top of the food web feed on contaminated food-mainly fish and marine mammal carcasses-thus accumulating high quantities of these chemicals. It causes birds like the bald eagle to lay thin-shelled eggs that dry out or break during incubation.
So far, this hasn’t been the case on the northern islands. Since 2002, 46 juvenile bald eagles have been released on Santa Cruz Island. Of those, 25 remain on the national park with several other bald eagles flying in from the mainland and Catalina Island. The deadly toxins appear to be less prevalent surrounding the northern islands. The most recent chick is the third successful nest since 2006. Its parents are from Catalina, and it’s their second successful nest on the largest of the Channel Islands.
“Our goal is to reestablish bald eagle nests on all the park islands,” said Dave Rempel, a biologist for IWS, who has been involved with the restoration of bald eagles on the chain since 2002. “Every island historically had eagle nests. It tells you how abundant the sea life was around the islands.”
There are eight California Channel Islands. Specifically, those goals include two dozen nesting pairs on the five park islands (Santa Barbara, Anacapa, Santa Cruz, Santa Rosa, and San Miguel) and another dozen total nests on Catalina, San Clemente, and San Nicolas islands.
However, there are a lot of unknowns out there. It’s not entirely known what levels of contamination bald eagles are carrying on the national park. For instance, the levels of contamination of bald eagles hanging out on San Miguel could be higher because they scavenge more on marine mammal carcasses; four types of pinnipeds numbering well into the thousands reside on the windswept isle.
“It’s promising that we’ve had three successful nests, but we need to recapture more birds,” continued Rempel. “Toxicologists are trying to project the levels of DDT. Marine mammals seem to carry the highest load. The good thing is the older birds seem to spend most of their time fishing.”
When eagles are recaptured, biologists take blood and tissue samples to analyze levels of contamination. So far, DDT levels are relatively low compared to the Catalina birds. Rempel said that was to be expected farther from the source, but it will take several more years to determine if bald eagles can sustain themselves.
In the meantime, last year’s eaglets (now known as A60 and A49) are doing well. A49, the first chick born on the Channel Islands since the last known successful nest on Anacapa Island in 1949, is flying back and forth between Anacapa and Santa Rosa islands.
A60’s parents were the ground-nesting pair at the southern end of Santa Cruz. A true oddity, biologists can’t confirm any other ground-nesters in the lower 48 states. Typically, bald eagles nest in treetops and cliffs. Most ground nesting occurs in the frigid Aleutian Islands off Alaska because there are no trees. That eagle is also doing well, exploring the rugged archipelago. Its parents returned to the same depression on the grassy hillside this past spring, but abandoned their nest this time.
Parents that survive and have successful nests return to the same nest site year after year. Rempel said there’s a nest on Catalina that a pair has used for 20 years that’s a half size larger than the one currently in use on Santa Cruz.
“We’ve seen three new pairs [of bald eagle mates] on Anacapa, Santa Cruz, and Santa Rosa,” said Rempel. “We haven’t seen them building nests. They’ll pair bond for a year or two before starting one.”
Now at the base of the bishop pine, biologists placed a hood over the newest eight-week-old eaglet to keep it calm. One biologist held open a mottled wing, the other drew blood for testing. Then a silver band was placed on a leg just above a yellow talon. A blue tag signifying a park service eagle (Catalina eagles wear orange tags) was clipped to one wing. Finally, a Global Positioning System was fixed to the other to track its comings and goings across its island habitat.
Afterward, Spickler returned the eaglet to its lofty nest no worse for wear. As he descended, the loud cackling calls of the eaglet’s mother filled the canyon, checking in on the latest addition to Santa Cruz Island.