Climate change isn’t just a problem for rare or endangered species: It threatens some of the East Bay’s most common backyard and shoreline birds. On Sunday, Oct. 16, the second annual Berkeley Bird Festival will feature free sidewalk chalk drawing, bird-related crafts, tours of the U.C. Museum of Vertebrate Zoology and — if you sign up in advance — free guided bird walks. (Berkeleyside is a media sponsor of the festival.)
Get involved with Golden Gate Audubon or other conservation groups to help protect Bay Area birds from climate change
In conjunction with the festival, here are profiles written by members of Golden Gate Audubon Society of six local species at risk from climate change. A landmark 2019 report by National Audubon projected how 389 North American bird species will fare under different climate scenarios. Among them are the buffleheads, golden-crowned sparrows, pygmy nuthatches, surf scoters, fox sparrows and Nuttall’s woodpeckers commonly found in Berkeley.
Bufflehead: Flash and splash
Along the Cesar Chavez Park shoreline, a flash of movement and small splashes catch my attention. At first, I see only bubbles. Then five small ducks pop up on the surface of the water — one black-and-white one and four brown-and-grey ones. My eye is drawn to the iridescent green and purple head of the black-and-white duck, which contrasts with its bright white ear patch. The four other ducks have brown heads and small white cheek patches. Their dark brown eyes thoughtfully regard me before they once again dive beneath the water.
These ducks are all buffleheads — the one with the big colorful head a male and the rest females. Their funny name comes from the male’s large “buffalo”-shaped head. They are the smallest diving ducks in North America, with males averaging a compact 15 inches in length and females 2 inches smaller. Buffleheads are monogamous, a rarity in the duck world. Although they’ve been known to live up to 13 years, their typical lifespan is just two and a half years since they frequently become dinner for birds of prey.
I start looking for buffleheads in late October, when they can be found in small groups bobbing along the shallow open waters of the Bay or freshwater ponds like Lake Anza. Due to their small size and high metabolism, they spend most of their time hunting for aquatic crustaceans, mollusks, and insects. Like most ducks, they tend to forage by both day and night, sleeping on the water when they need a break.
Most of our buffleheads migrate in mid-April to their breeding grounds in the boreal forests of Alaska and central Canada, where they nest in tree cavities excavated by northern flickers. A day after hatching, the ducklings follow their mother to water and begin to eat.
Bufflehead numbers have recently been on the rise, reversing a historical population decline due to the destruction of wetlands for agriculture. But climate change now poses a new threat to these little ducks.
Buffleheads, like a number of other East Bay migratory species, are particularly threatened by potential changes to their breeding grounds in the far north, according to the Audubon report. Three degrees Celsius of temperature rise could result in two-thirds of buffleheads’ current breeding grounds becoming uninhabitable for them. Less summer habitat means more competition for food, fewer nesting sites and longer migration distances.
These tough little birds — with their sudden dives and eye-catching flashes of iridescent color — could be at risk of extinction in our lifetime. — Beth Reuter
Golden-crowned sparrow: Winter backyard visitor
Three descending notes of bird song bring me joy in winter. One day in early fall, I’ll hear a call that sounds like “Oh, dear me” and see a handful of golden-crowned sparrows hopping around my yard, pecking for seeds and insects. These birds that have just flown 3,000 miles from their summer homes in Alaska and western Canada may even be the same flock that visited me last year.
Golden-crowned sparrows form lifelong winter relationships. Flocking with friends reduces the need to fight over pecking order. With more energy to find food and escape predators, the birds increase their chances of surviving winter. In spring, the entire golden-crowned sparrow population returns to its remote breeding grounds and separates into couples who fiercely defend their nesting territories.
The scientific name for this species, atricapilla, means “black-haired” for the black cap that extends from their sturdy bills past their ears. In summer breeding plumage, a bright blaze of yellow sweeps the top of their crowns. Their full-chested stoutness, long tails and dramatic black-and-yellow heads give these otherwise brown and grey sparrows a stately look. According to UC Santa Cruz scientists, bold crown colors signal stronger fighting abilities. Birds who are strangers use these “badges of status” to establish dominance levels without having to fight. Birds who already know each other stick to established hierarchies even after researchers artificially brighten their colors.
Golden-crowned sparrows are part of the genus Zonotrichia, which also includes locally common white-crowned Sparrows. The two species often intermingle at feeders and are easy to confuse, especially in the fall when their crown colors are duller. White-crowns typically can be identified by their pink, orange, or yellow bills versus the dark or dusky grey bills of golden-crowns.
In spring, golden-crowned sparrows gather in large flocks before leaving for their long flight north. The sparrows time their departure so their young will hatch when the most food is available in the tundra’s short summer season.
Climate change may lead to early spring heat waves, which can endanger young birds in the nest. If temperatures rise by 3 degrees Celsius, National Audubon estimates that a whopping 85% of their breeding grounds will be lost — no longer providing the food and nesting materials needed by the sparrows. Their wintering grounds will shift away from the Bay Area up towards the cooler Sierra.
During the Gold Rush, disappointed miners interpreted the golden-crowned sparrows’ three whistled notes as “No gold here.” Unless we can minimize climate change, we in the Bay Area may end up voicing a similarly sad “No golden-crowns here.” — Jennifer Morrow
Pygmy nuthatch: Small and sociable
They are so small. One birder commented, “Teeny-tiny little buggers, but cute as hell.”
Their common name is descriptive: pygmy nuthatch. “Nuthatch” because of their behavior of jamming large nuts and seeds into tree bark, then whacking them with their sharp bill to “hatch” out the seed. “Pygmy” because they are the smallest of the nuthatches. No longer than 4.3 inches, they weigh just .37 ounces. That’s just slightly larger than our local hummingbirds.
With its relatively large, rounded head, no discernible neck, and a straight, sharp bill, a pygmy nuthatch could be imagined as a feathery ball small enough to fit in the palm of your hand. The lower half of its body is white and its pointy beak and eyes are black, but everything else is gray: gray wings, gray crown, and gray tail, which is almost as long as its body. Males and females are the same color.
To say that they’re active birds is an understatement. Continually chirping, they make a series of jerky movements up and down the sides of conifers looking for insects. They’re the only bird that can walk down a tree and hang upside down from tree branches, especially Ponderosa Pines. They also forage on the ground for seeds.
Their most frequent call is a shrill, staccato piping, sounding a bit like Morse code or an old-timey typewriter. They flap their wings while striking the bark of a tree to enlarge existing woodpecker holes. Pygmy nuthatches stash seeds and nuts in crevices in bark for later eating; they’ve been observed using bark or lichen as tools to cover the food they’re saving for winter.
Pygmy nuthatches live in the Bay Area year-round. They’re highly sociable, creating multi-family groups that roost together for warmth in the winter months. In spring and summer breeding season, up to 100 may occupy a single nest cavity and help construct the nest, incubate eggs and feed fledglings. Breeding pairs get help from their own offspring from previous years. They’re sociable toward humans, too: They readily eat suet from feeders hung near their familiar habitat and have even been seen eating sunflower seeds from a person’s hand.
Locally, you can find Pygmy Nuthatches in the East Bay Hills, including Vollmer Peak in Tilden Park and Strawberry Canyon. Globally, they’re found across the North American west. But climate change threatens a lot of their range. According to National Audubon, a 3-degree Celsius temperature rise would reduce their summer breeding area by 84% —effectively eliminating pygmy nuthatches from almost all of the U.S. and Mexico, and leaving them with only a small livable area in Canada. — Sandy Gess
Surf scoter: Bright-faced black duck
Once you see a male surf scoter, you’ll remember him. The large multi-colored bill — black by the head, orange in the middle, and yellow on the tip, with white splotches holding a black spot on either side — makes this duck conspicuous. His black coat is broken by white on his forehead and the back of his neck. The smaller, grayish female also has two white face patches but a plainer large black bill.
The surf scoter is a large duck — 2 pounds and 18 to 20 inches from tip of bill to end of tail. A few scoters stay here year-round but many more come for the winter, feeding in sea grasses near the shore and “rafting” in deeper water in groups that can number into the hundreds or even thousands. Look for them off the shores of McLaughlin Eastshore State Park, Cesar Chavez Park and the Berkeley Marina.
Although they winter in salt water, surf scoters breed near small mountain freshwater ponds in Alaska and northern Canada. The female does all the work, laying six to nine eggs in a depression in the ground, incubating them for about three weeks, and then walking the sooty-grey chicks to shallow fresh water, where she teaches them to catch small bugs and other water creatures. She shades the chicks until they can control their body temperature; chicks die in heat waves. Young scoters are also killed by predators, mainly gulls.
Both adults leave the breeding ground when the chicks are full-grown but still developing their flying muscles. They travel to a sheltered location to shed worn feathers and grow new ones before migrating south. Once the young birds can fly, they also head south. Surf scoters winter along both coasts; in the Pacific they spread as far south as Baja California, where they feed on invertebrates like mussels and barnacles. Large flocks gorge on herring eggs throughout San Francisco Bay in spring, storing the fat needed to fuel their strenuous migration to Alaska and Canada.
These stunning ducks are particularly threatened by oil spills, since oiled feathers don’t hold body heat: About 4% of the surf scoters in the Bay died in the 2007 Cosco Busan spill. Meanwhile, red tides such as the Bay’s recent algal bloom can seriously decrease their food supply.
However, the biggest long-term threat to scoters is climate change. Data from Golden Gate Audubon’s annual Oakland Christmas Bird Count show that scoter numbers in the Bay have already dropped dramatically over the last 30 years. A 3-degree Celsius rise in temperature would reduce their summer breeding grounds by an estimated 62%. Meanwhile, warming coastal waters could cause more red tides and push winter populations further north to the Vancouver and Alaska coasts. If climate change continues, San Francisco Bay could become a little duller without the distinctive orange flash of male surf scoters’ bills. — Marjorie Powell
Fox sparrow: Watch those feet!
I remember distinctly the first time I saw a fox sparrow: a chocolate brown bird hopping and scratching vigorously in leaf litter under some tall redwoods, oblivious to the birdwatchers nearby. I thought to myself, “Gee, that sure is behaving like a hermit thrush.” But the color and pattern weren’t quite right, and the bird was too small. “Sort of like a song sparrow,” I thought, but that wasn’t right either. Sensing my confusion, a birder behind me said “fox sparrow” — a new bird for me that’s become one of my local favorites.
The fox sparrow is one of the most variable species in North America, with 18 subspecies that are divided into four distinct groups based on appearance: red, slate-colored, large-billed, and sooty. The most common variety in the Bay Area is the sooty fox sparrow, distinguished by its dark brown (sooty!) plumage and relatively short tail. The easiest way to identify them is by their behavior — the hopping and scratching in leaf litter under mature trees that first captured my attention. Birds of the World describes this foraging technique as a “double scratch,” meaning that both feet move synchronously, almost like a mechanical wind-up bird.
Just as there’s considerable variation in appearance, so there are differences in their migratory patterns, even within a group. Some subspecies of sooty fox sparrows are altitudinal migrants, meaning they travel relatively short distances from coastal areas to higher elevations in the Sierra, while others undertake one of the longest known journeys over water by a land bird, from Southern California to the Aleutians.
Our Bay Area sooty fox sparrows typically spend the winter here and leave each spring to breed along the coast of southern Alaska, although we get a few of the large-billed subspecies breeding here. (If you see one of these, you’ll know it. Not only is it longer-tailed and reddish in color, but its scientific name, megarhyncha, means “big nose,” a very apt description.)
Higher temperatures from climate change would reduce the winter range for fox sparrows in the southeastern United States and in California’s Central Valley, but the Bay Area and Northern California coast would still remain habitable for them. The picture looks much grimmer in the summer, according to National Audubon. While fox sparrows could gain some breeding territory in the very far north of Canada and Alaska, a 3-degree Celsius temperature rise could eliminate 72% of their current breeding areas. And less breeding territory in the north would mean fewer fox sparrows returning to the Bay Area each year with their distinctive “happy feet” foraging moves. — Eric Schroeder
Nuttall’s woodpecker: Built for banging
Often heard before seen, Nuttall’s woodpecker has a brief rattling call reminiscent of a referee’s whistle.
Intermediate in size between downy and hairy woodpeckers, you can tell a Nuttall’s by the pattern of alternating black-and-white bars across the back. Adult males and females are of similar size, but males have a crimson crown at the back of the head. Juveniles of either sex also sport red head feathers.
Nuttall’s woodpecker depends on oak woodlands as a source of food. This active, agile forager hops along tree trunks and branches, probing and prying up bark with its bill in search of beetle larvae, caterpillars, other insects, arthropods, berries and seeds. It also relies heavily on riparian habitat to construct nest cavities in various softwood trees, such as sycamore, willow and cottonwood.
Nuttall’s and other woodpeckers possess amazing anatomical adaptations to help them with cavity construction and feeding. A flexible tongue with a pointed, barbed tip extends to capture food and then wraps around its skull, inside its head, when retracted. Thick membranes shield its eyes from wood chips and protect its ears from the sound of hammering. You could say these birds are built for banging! Bill placement perpendicular to a tree directs the impact of bark-banging below its brain. A recent video study of woodpecker hammering concluded that the bird’s skull doesn’t absorb the shock of these blows, and the brain is not put under enough pressure to cause a concussion.
A shallow keel on the breastbone brings the bird’s body closer to a tree trunk, and a flattened bone formed of fused tail vertebrae, called a pygostyle, helps the tail feathers prop against the trunk for extra upright stability. The foot has two toes each pointing forward and backward, which provides a stronger grip.
Nuttall’s woodpeckers are found year-round throughout much of California — and only in California, except for small populations in northern Baja California and occasionally Oregon. In the East Bay, you’re most likely to see and hear them in forested portions of our parks or visiting backyard suet feeders.
National Audubon estimates that, with 3 degrees Celsius of temperature rise, Nuttall’s woodpeckers will lose over two-thirds of their current range, especially that part in Central and Southern California. More frequent and intense wildfires and heat waves could push them towards the coast and north into Oregon, but they’ll lose much more territory than they gain. Nuttall’s woodpeckers may be perfectly evolved to weather blows of head-banging — but not the relatively sudden climate changes brought on by our fossil fuel dependency. — Blake Edgar
For more information on climate risk to birds, see National Audubon’s Survival By Degrees report, which includes maps of projected summer and winter ranges under various climate scenarios for 389 North American bird species. If you’d like to get involved with Golden Gate Audubon’s efforts to protect Bay Area birds from climate change and other hazards, contact climate@goldengateaudubon.org.