By Miya Lucas

In the spring and summer, the song of the California Thrasher always puts a smile on my face.  The rapid pulsing, throbbing beat within a continuous melody reminds me of a rhythmic rap song. Often lasting three to five minutes, it’s one of the more varied and complex bird songs and lacks a characteristic, repeated phrase that is easily identified with that bird.

The Cal Thrasher belongs to the Mimidae song bird family. “Mimid” means mimic in Latin, and other Mimidae include our familiar Northern Mockingbird and the Gray Catbird of the East Coast. Although the Cal Thrasher mimics a wide range of species including American Robin, House Finch, and Northern Flicker, mostly it’s known for its own complex song.  One study found 2,807 phrases in a single Cal Thrasher song! Some phrases are repeated like the chorus in your favorite pop song, while others are used only once.

Although you can hear California Thrashers year round, spring and summer are when they’re most vocal.  Even when they sing, it can be hard to spot them. They tend to perch on the middle or side branches of shrubs and trees rather than the top, and their brown heads, wings, and tails camouflage well in the undergrowth.

California Thrasher singing by Miya Lucas

Both female and male thrashers sing. Their songs are usually used for announcing and protecting territory, and mostly sung by the males.  However, if a male bird is clashing with another male who is encroaching into his territory, the female will “stand guard” and start singing until the male returns.  Once the male returns, the female often stands down and stop singing.

Cal Thrashers mate for life, and both male and female help raise the young.  If they have a second clutch, the female typically leaves the first brood while the male stays and continues to feed the chicks.

Males and females look similar. Juveniles have more yellow bordering their underwings than the adults.  The adults have darker bills, while the juveniles’ are brownish. Juveniles’ feet are also more brown, while the adults have dark gray to black feet.

The California Thrasher’s most distinctive visual feature is its long, decurved bill, which it uses to mow through grass or leaves like a farmer using a scythe.  This foraging behavior may be the source of its name – thrashing through leaves and mulch to find insects, spiders, berries, and seeds.…

When Doug Bell heard that a pair of Peregrine Falcons was nesting on the Campanile, he couldn’t believe his luck. An avid falconer, Bell has been fascinated with Peregrines — the fastest animal in the world — since he was a kid growing up in Berkeley. He received his Ph.D. in zoology from UC Berkeley, where he studied ornithology and systematic biology. But never before had he heard of Peregrines nesting on top of the campus’s 300-foot-high bell tower. “It blew me away,” says Bell,  a wildlife program manager with the East Bay Regional Park District.

Peregrine Falcons were once on the brink of extinction, in large part due to widespread use of the pesticide DDT and the country’s misguided assault on predatory animals. In the early 1970s, however, Peregrine Falcons caught a break. DDT was banned and the Endangered Species Act was passed, among other wildlife regulatory laws. In the years since, peregrines have made a remarkable comeback.

As the numbers of Peregrine Falcons have increased, they’ve begun moving from their natural cliff faces into urban areas, laying their eggs on skyscrapers and other tall buildings, such as the Campanile. The following is an interview about the UC falcon pair with Doug Bell and with Golden Gate Bird Alliance member Mary Malec. It’s by Anne Brice, reprinted with permission from Berkeley News, part of the UC Berkeley Office of Communications and Public Affairs.

The female Peregrine Falcon on the second balcony ledge of the Campanile, close to her nest (Photo by Doug Bell)

Berkeley News: When did you first hear about the peregrine falcons nesting on the Campanile?

Doug Bell: I first heard about them in early April. [Birdwatcher Kathleen Durkin, who runs a computing lab in the College of Chemistry, first spotted them.] I thought, gosh, you know, I want to check it out. So on the weekend, I was watching them and it sure looked like they were nesting there. Falcons don’t build nests — they just use a substrate like soil or gravel and make a little depression in it. That’s nice for cliff faces, where they nest in natural situations, but for buildings and skyscrapers that just have cement or steel, there may not be enough substrate around to cradle the eggs, so the female can’t incubate them well. I thought, “We gotta get something under those eggs, so they at least have a good shot at incubating.”…

By Diane Rooney

Like many of us, you’ve probably seen – and perhaps become addicted to – the live streaming Osprey nest cam that Golden Gate Bird Alliance launched at the end of March. You may have watched Osprey parents Rosie and Richmond work on the nest and incubate their eggs, and then cheered when their two chicks hatched in mid-May.

But how did this stunning, intimate video feed from the nest come to happen?

The story of the Bay Area’s first Osprey nest cam is a saga of vision, passion, and cooperation between individuals and organizations. It’s almost as astonishing as the story of how Osprey populations have rebounded from decimation by DDT over the past 30 years!

The project was the brainchild of GGBA Executive Director Cindy Margulis, who had watched Ospreys nesting in Richmond even before joining the staff of GGBA, and daydreamed about getting a closer look into the lives of local Ospreys.

Her dream became scientifically relevant through the work of Tony Brake, a Golden Gate Raptor Observatory volunteer who has been leading a citizen science effort to find and monitor all Osprey nests on the edge of San Francisco Bay since 2013.

Ospreys had never been known to nest directly along the Bay before the 1990s. But Tony’s study, first published in Western Birds, documented a nesting trend on San Francisco Bay.

That research validated the phenomenon and meant that more insights into Osprey nesting on the Bay would help us support this exciting trend. A nest cam could create a big educational opportunity for the whole Bay Area – not just engaging avian scientists and bird lovers, but also sparking children, families, animal lovers, educators, photographers, and others to marvel at these unique raptors trying to live in our midst.

From the outset, the camera was meant to inspire learning and motivate people around the Bay to help these birds thrive by making the Bay’s watersheds and shoreline environment clean and safe.

That was the vision part. Then came the passion and cooperation.

The Osprey nest cam was a complex project involving many stakeholders, supporters, and helpers. The target site was an existing Osprey nest atop the Whirley Crane, a decommissioned World War II-era maritime crane. The crane is part of the Rosie the Riveter WW II National Home Front Historical Park interpretive footprint, but it stands next to the Richmond Museum Association’s SS Red Oak Victory ship museum and is owned by the Port of Richmond.…

By Daryl Anne Goldman

It’s breeding season — an opportunity for birders to watch courtship rituals, nest building, eggs hatching, and parents caring for their chicks. It’s fascinating how much diversity there is among species in the number of eggs in a clutch, what the newly hatched chicks look like, and how dependent or mobile chicks are after hatching.

Did you ever wonder why the eggs of songbirds and owls hatch up to several days apart, while a clutch of duck eggs hatches within a few hours of each other? Why do duck eggs hatch within four hours when they are laid over the course of several days?  These questions got me wondering about the parental contributions to this process, and whether the embryos do anything to directly influence this.

With a little research I learned that here are two types of hatching strategies — asynchronous and synchronous.

Asynchronous hatching

Asynchronous hatching is when the eggs of a clutch hatch over a period of a few days.  The time between the first and last egg hatching can be as much as 14 days, as with the Barn Owl.   With this hatching strategy, incubation usually starts before the later eggs are laid.  There is a higher rate of mortality with this hatching strategy, and the last chick is usually not expected to survive and is more of an insurance policy against the loss of the first offspring.   It’s much like the British monarchy: You need an heir and a spare.  In some species the firstborn, stronger chicks or even the parents may push the weaker, last born chicks out of the nest.

Asynchronous hatching, by Maja Dumont

What are the parental contributions to asynchronous hatching? The female deposits differing amounts of hormones, immunoglobulins, and antioxidants in the yolk, albumen, and shells of the eggs she lays, which then affects the survival of each hatchling.  For instance, in some species yolk antioxidant and immunoglobulin concentrations may decrease across laying order, thus handicapping the immune system of the last hatched chicks. However, in the same species, yolk testosterone concentrations may increase with laying order, which may compensate for poorer immune function by helping accelerate growth and food begging rates.

Does the embryo have a role? There is some research showing that bird embryos can actively modify the action of the hormones deposited in the yolk, and use maternal steroids to benefit their own fitness.…

By Ilana DeBare
On the road again… to Oakland!
After a month’s hiatus for Birdathon, Golden Gate Bird Alliance’s traveling Centennial exhibit has returned to public view, now at Oakland’s City Hall complex.
The main Centennial exhibit of 14 colorful panels is open during business hours in the lobby of the city’s Dalziel Building until July 7.  In addition, we have a photo exhibit of Oakland and Alameda wildlife on the third floor of City Hall, just outside the City Council Chambers.
If you haven’t had a chance to view the exhibit yet, come by and bring a friend! You can expand your visit into a full morning or afternoon outing by adding a mini-field trip — strolling over to the nesting colony of Black-crowned Night-Herons and Snowy Egrets just a few blocks away.
The Centennial exhibit in the Dalziel Building lobby / Photo by Ilana DeBare
Passerby views the Centennial exhibit. Photo by Ilana DeBare
Snowy Egrets nesting in street trees, just a few blocks from City Hall / Photo by Ilana DeBare
Although the bulk of breeding season is past, you should still be able to see nesting herons and egrets — some with a second clutch if they lost their first — through the middle of June. Golden Gate Bird Alliance volunteers have been monitoring the trees for fallen young herons, and we are partnering with Oakland Zoo and International Bird Rescue to retrieve, heal, and release the injured juveniles.
Then round out your visit to the Centennial exhibit and the heron colony with lunch downtown! See below for some good Oakland eateries near City Hall and the rookery.
It’s fitting that the Centennial exhibit find a roost at City Hall. Golden Gate Bird Alliance has a long history with Oakland residents and wildlife, including:

• GGBA member and conservation chair Paul Covel served as the City of Oakland’s first paid naturalist from 1947 to 1972. He introduced thousands of children and adults to the wildlife of Lake Merritt and the Oakland Hills, established a refuge for injured birds at Lake Merritt, and marshaled support to build the Rotary Nature Center there.
• GGBA fought long and hard to preserve wetlands along San Leandro Bay, an area that today includes the city’s beloved Martin Luther King Jr. Regional Shoreline. Thanks to a GGBA lawsuit in the 1980s, 73 acres of wildlife-rich marsh there were saved from development and turned into parkland.

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