ALL PHOTOS BY CHUCK GRAHAM
It was a good old-fashioned dustup. Throngs of western gulls in a cacophony of keow, keow, keowing carried on over guano-covered Scorpion Rock near the southeast end of Santa Cruz Island, the largest isle at the Channel Islands National Park, but something was amiss while I watched with intrigue from my kayak. There was one bird, not gull-like, that was definitely stirring the pot. It was a peregrine falcon wreaking havoc among the agitated flock of gulls.
The fastest-flying bird in the world was in full predatory mode. It was June, nesting season for western gulls and their hungry, helpless chicks that were left dawdling out in the open. Sure enough, there was the peregrine taking its pick of the unaware. With its wings tucked in and reaching speeds north of 200 mph, it doesn’t take much for a peregrine to finish off a fuzzy western gull chick in an all-out dive.
What the peregrine underestimated, however, was the reaction it got from all the other gulls on Scorpion Rock. I was able to count at least 10 gulls attacking and chasing the peregrine. They eventually forced the raptor to drop its prey in a plume of dust, but what the gulls overlooked was that this peregrine wasn’t alone. While the initial peregrine hid from all the gulls underneath a deep, knobby alcove, its partner in crime swooped in out of nowhere and grabbed the bedraggled chick, flying it off to its sheer, cliffside aerie.
“They’re hard to watch in the field,” said biologist Peter Sharpe of the Institute for Wildlife Studies (IWS), who has been integral in the recovery of bald eagles and peregrines alike on the Channel Islands. “They feed almost entirely on birds.”
Peregrines by the numbers
There was a time when all eight California Channel Islands had peregrine falcons, but by 1955 they had vanished. Montrose Chemical Corporation was the company that developed dichlorodiphenyltrichloroethane, or DDT, pesticides. From 1947 to 1971, Montrose had dumped 1,800 metric tons of DDT into the ocean near Santa Catalina Island. By 1972 there was a total ban on DDT in the U.S., but the damage had already been done. The chemicals worked their way through the food web and by 1970 the peregrine falcons of North America and the Arctic were listed as endangered. By 1975 there were only 324 known nesting pairs left in America.
Just as with bald eagles and California brown pelicans, DDT pesticides forced peregrine numbers to decline to critical lows. Just like those species, peregrine falcons were forced to lay thin-shelled eggs, and those eggs would then get crushed by the parents while in the nest before they could hatch. It wasn’t long before the skies over the islands were absent of what is now the most widely spread predatory bird in the world. In fact, there are 19 subspecies of peregrine falcons in the world, and the only continent where peregrines are not found is Antarctica.
In 2002 and after 25 years of litigation, Montrose was court-ordered to pay $140 million with at least $30 million going toward the recovery of natural resources like the return of peregrines to the Channel Islands.
Aggressive captive breeding of peregrine falcons began in 1974 with 6,000 falcons being released. Currently there are 3,000 breeding pairs in the wild, spread out among Canada, the United States and Mexico. In the 1980s, 37 captive-bred peregrine falcons were released across the Channel Islands.
“Since 1992-93, eggshell thinning has lessened almost each year,” continued Sharpe. “The current population exceeds the predicted historic levels.”
Recovery efforts for peregrine falcons also involve a lot of groundwork, so some of that $30 million goes toward surveying potential habitat. Certainly, the habitat is there, but locating occupants is another matter.
“It’s hard to get around,” explained Sharpe, referring to the Channel Islands’ craggy coastlines, unpredictable winds and currents in the open ocean and their steep, rocky marine terraces on land. “There’s a lot of footwork, boat surveys.”
When looking for peregrine falcons one usually hears them before seeing them. There’s no denying their calls of kak, kak, kakking. Once that’s been confirmed there’s a thorough scan with binoculars and hopefully the discovery of an aerie — their concealed nest site set high up on a cliff face and out of the wind is revealed.
Peregrines are large, powerfully built birds of prey about the size of a crow. With a black hood, blue-black upperparts and creamy white chin, throat and underparts, they are finely barred from the breast to the tail. The long, tapered wings have a straight trailing edge in flight and the tail is relatively short. The eyering is yellow, with the heavy bill also yellow, tipped black. The females are 25 percent larger than the males. Their multitude of colors allow them to blend in well with their rugged surroundings.
Peregrine means “wanderer” in Latin. Many peregrines travel over 15,000 miles in a given year. Fortunately, the peregrines on the Channel Islands enjoy their open ocean environment. There are plenty of species of seabirds to keep them occupied. There are at least 17 nesting pairs on mountainous Santa Cruz Island, the most biodiverse isle off the California Coast. Windswept Santa Rosa Island has at least eight breeding pairs. There may be as many as four nesting pairs on narrow Anacapa Island and three nesting pairs on tiny Santa Barbara Island. At this time, it’s not known what the numbers are on San Miguel Island.
“When surveying, you’re relying on their sound and flying,” said Sharpe. “Typical surveys last for four hours. If they just sit there they are almost impossible to spot.”
So when peregrines are making it tough for biologists to locate them, Sharpe and Nate Melling, a field supervisor for the bald eagle/peregrine falcon project for IWS, enhance their surveys by playing back peregrine calls. They play the calls for a minute and then wait. Over time they’ve been rewarded with a 58 percent response rate.
“It’s a very effective technique,” explained Sharpe. “Then we try to locate a nest or a depression in an alcove. It’s tough to see the chicks so we look for behavioral changes in adults.”
Once the aerie is located, Sharpe and Melling attempt to band as many of the chicks as they can.
Band on the run
The live peregrine cam supplied by www.explore.org, a high-end web cam revealing the everyday lives of peregrines during the breeding and nesting season, is an up-close look into the behavioral traits of these magnificent raptors. This is the first completely natural peregrine webcam not on a building ledge. In early May 2018, the cam had revealed three healthy chicks in the aerie not venturing any farther than their lofty ledge overlooking the east end of the Santa Barbara Channel from the north side of Anacapa Island.
Then, not long after, during one gloomy May Gray morning, the cam revealed only two fuzzy white chicks. Peregrine falcons aren’t the only birds tending to their nests on Anacapa Island. Western gulls dominate the windswept isle and will take advantage of any opportunity when it comes to a meal. Apparently while the peregrine parents were away, an adult western gull had raided the aerie, nabbing one of the unattended chicks. It was a fearless move to say the least, but not surprising considering that these are foes inhabiting the same island.
“We don’t really know how common that behavior is in our area — one reason the camera is so cool,” said Melling. “But predation of young nestlings is generally not super uncommon. Ravens are common culprits. On the mainland, great horned owls are known predators of various raptor nestlings. Given the sheer density of gulls on Anacapa, it would be reasonable to assume that such predation by gulls is not incredibly uncommon. They are pretty opportunistic foragers.”
The Vanguard plowed through choppy, northwest seas out of the Channel Islands Harbor in Oxnard. I was fortunate enough to be tagging along with Sharpe and Melling on a peregrine banding out on wave-battered Anacapa Island. Typically, they band peregrine chicks at 18-20 days of age.
After climbing the steep staircase on East Anacapa Island, we walked toward Inspiration Point on the north side of the island. From there we dropped over the edge of a steep cliff on the leeward side of a sheltered cove. Immediately the peregrine parents began divebombing us, and on several occasions passing within a couple of arms’ reach of us.
The chicks had wedged themselves as far back as they could in the rear of their cliffside aerie, but Melling deftly removed each bird for its exam. Once in hand, the chicks were placed in a sack to calm them down. Once both chicks were secured, Sharpe and Melling worked efficiently and swiftly to band the birds. A silver band has a number on it that will never be used by another bird.
“It can only be read if the bird is in hand,” said Sharpe. “We need more banded birds out there.”
They also extract blood, measure and weigh the cotton ball-like chicks. Melling gently held each chick so Sharpe could take blood. Blood was taken to do genetics and check for any contaminants.
Another vital source of information is the removal of egg shells and remnants of prey items from the aerie. Current egg shells are measured for thickness and compared with pre-DDT shells. Prey items are collected to see what these raptors are eating. Other peregrine nests on the Channel Islands have revealed 74 species of birds, including remains of Cassin’s auklets, pigeon guillemots, red-necked pharalope, western gulls and house finches.
One interesting item in the aerie on the north side of Anacapa Island was the whole egg of a Scripp’s murrelet, a small, nocturnal seabird that breeds and nests on the Channel Islands. Apparently one of the peregrine parents had killed and brought the tiny seabird to the aerie where the pregnant bird was devoured but somehow the egg was left intact.
After Sharpe and Melling finished their work with the peregrine chicks on the north side of Anacapa Island, we walked on the outer edge of the southside of the isle. The two sides are less than a mile apart. Suddenly a swoosh from above; it was peregrine in a full dive. A big swoop and then it flapped its wings furiously only to be met by its mate in midair. Was there an active aerie nearby?
Sharpe and Melling were scanning with their binoculars, watching for behavioral traits in the potential parents. The two biologists peered over several precarious cliff edges searching for an aerie, but nothing materialized. We did manage to get some photos of the adults and noticed that at least one of the peregrines had a band on its leg.
It was time to catch the boat back to Oxnard. After a day trip on East Anacapa Island, Island Packers is always good for taking visitors to the south side of the island to see seals and sea lions hauled out on the wave-battered rocks, but we went a little farther as Captain Jason allowed us to look for the new peregrine aerie. The sheer cliffs were honeycombed with potential sites, but the two adult peregrine falcons were nowhere to be found and we couldn’t hear their calls over the boat’s motor.
Suddenly, Melling called out while looking through his binoculars and pointing toward the 300-foot-tall cliffs. “There it is, just to the right of the big rock with all the bird crap on it.”
Sure enough, there was a fuzzy, white peregrine chick teetering on the edge of its aerie. It was certainly bigger than the other chicks at the previous aerie and it had some coloring on its wings already, an older nestling peering out over the ocean. At six weeks it will be ready to fledge, and hopefully one day soon it will establish its own territory on the Channel Islands.