Animal phenomena abound in the East Bay, so here’s where to see ladybugs converging, newts migrating, and night herons nesting. Or maybe you’d rather lay eyes on grunions, tarantulas, prairie falcons, harbor seals, and other critters.
It’s no secret that it’s hard to find living spaces and partners in the Bay Area, but who knew that the wild things are equally challenged when it comes to finding love and shelter in this iconic landscape? Faced with loss of habitat, some have turned to industrial sites and urban cores for solutions. Others are delaying overwintering or choosing to breed in the East Bay for the first time on record. Still others are struggling as drought, wildfires, and floods take their toll. And then there are a few who appear to be thriving, thanks to improved water quality regulations and public investment in restoration efforts around the bay.
This guide seeks to direct the curious to just a smattering of these unusual wildlife gatherings. But before you go, remember it’s illegal to remove wildlife from California parks, and don’t forget to bring binoculars, hydration, and protective gear. Whatever you do, leave the site the way you found it, and consider involvement in citizen scientist projects that collect and share information about these beloved creatures.
Ladybug Aggregations
Where: Stream Trail, Redwood Regional Park, Oakland
When: October through March
Convergent ladybugs have a reputation for being voracious munchers of aphids, but it’s a less well-known fact that when the winds of fall pick up, these tiny reddish-orange beetles ride the air currents into the hills, where they stop eating and form million-strong aggregations.
“Just like hibernating bears, ladybeetles rely on fat reserves for the duration of the winter,” said Andre Szejner Sigal, an integrative biology Ph.D. student at UC Berkeley.
The Stream Trail in Redwood Regional Park is a favorite aggregation spot, but what makes this path so attractive? Szejner Sigal said the beetles in the Bay Area like to shelter in leaf litter that is exposed to the afternoon sun and lies close to a creek, and are attracted by pheromones, or chemical signals, that other ladybugs have left at the site.
“Lady beetles basically leave footprints, which the new generation follow,” Szejner Sigal said.
The beetles mate at winter’s end, then return to valleys to lay eggs, but in recent years, they have delayed overwintering until October and have not left the site until March. So, Szejner Sigal is conducting experiments to determine if these large groupings protect the beetles and if an increasing frequency of extreme weather events, as predicted under climate change, will deplete the beetles’ overwintering reserves faster.
This species of ladybug is not considered threatened, but protecting its overwintering sites is crucial: “When ladybugs gather in a small area, they are the most vulnerable to the effects of habitat loss,” Szejner Sigal said.
His advice to visitors? Walk carefully and focus on minimizing disruption. “Most of the beetles are under the leaf litter, so when you see a gathering, you could be only looking at the tip of the iceberg.”
Other ways to help? Plant native gardens and participate in Cornell University’s Lost Ladybug Project: LostLadybug.org/participate.php.
Photo Pxhere.com
Newt Crossings
Where: Tilden Regional Park, Berkeley
When: November through March
Why did the California newt cross South Park Drive? To get to the other side and breed. Seriously.
Newly hatched newts look a bit like tadpoles, but they soon metamorphose into warty young adults with slate-gray backs and bright orange-yellow underbellies. These youngsters abandon their natal pool in search of abandoned burrows and anywhere else moisture is trapped the minute the dry season approaches. But once rain returns, the newts migrate back to their natal pool to breed.
In Tilden, this annual migration finds many newts crossing South Park Drive on their way to Wildcat Creek, while others cross Wildcat Canyon Road to the Regional Parks Botanic Garden and Tilden Park Golf Course. As a result, park managers close South Park to cars from November through March — a seasonal ban that allows pedestrians to observe these slow-moving amphibians undisturbed with the caution that newts are poisonous if eaten, making them of concern to dogs.
Tammy Lim, a resource analyst with East Bay Regional Park District, observed that the newts are not an officially threatened species, but their population has decreased over the past several decades, primarily due to habitat loss. Lim recommended keeping boots and gear clean to avoid moving around Batrachochytrium dendrobatidis, or Bd, a fungal pathogen that attacks amphibians and is likely ubiquitous in parks. The good news? Owing to their toxicity, newts have few natural predators, other than garter snakes.
Photo by Dave Strauss
Night Herons Nesting
Where: Downtown Oakland, from Oak to 14th streets, and Lake Merritt
When: February through August
Each spring, hundreds of black-crowned night herons nest in groves of mature trees on downtown Oakland’s streets between Harrison and Oak streets, making this gathering the largest concentration in the Bay Area, which is an important breeding area for this species. But the colony’s position at the heart of the urban core is far from ideal, thanks to the tendency of some heron chicks to elbow weaker siblings out of the nest and onto unforgiving sidewalks and roads.
Two years ago, the community lent its support to a unique heron protection plan that took advantage of the planned removal of rookery trees for development projects to lure the colony back around Lake Merritt. Decoys, sound systems, and real nests were placed in trees by the lake. So far, this experiment has had mixed results, but now, under pressure from elementary students, bird advocates, biologists artists, advocates, and volunteers, the city is poised to make the black-crowned night heron Oakland’s official bird.
The hope is that by giving herons an official status, the community will bring increased awareness that will help protect the beloved birds. As Park Day School fifth-grader Ezra Graham noted, “They are funky and nocturnal, just like Oakland.”
Golden Gate Audubon director Cindy Margulis said that these herons are found all over the world, but that Oakland is the real hot spot for them: “They are living in an urban corridor, surrounded by development and threatened by climate change,” she said.
Samantha Sammons, a biologist with the Conservation Society of California, agreed.
“These birds are critical to the health of wetlands but are greatly threatened by climate change,” Sammons said, noting that by 2080, only 12 percent of their summer range will remain in North America.”
Yikes. All the more reason to participate in a citizen science project that monitors the Lake Merritt night-heron relocation effort.
Photo by Dave Strauss
Grunions Dancing
Where: Crown Memorial Beach, Alameda
When: May through August
For most of their lives, California grunion dwell quietly in near-shore waters, dodging birds, larger fish, harbor seals, and other predators. But during an annual spawning event that occurs on three or four nights following the full and new moons, thousands of these small silvery fish abandon the water to swarm onto open, gently-sloping, sandy, wave-swept beaches.
Typically grunion runs happen in Southern California, and all the way down to Baja California, but in recent years, they have been recorded along Alameda Island’s shoreline, said East Bay Regional Park naturalist Susan Ramos.
“They’ve started to lay eggs on Crown Beach,” Ramos said, noting that grunion were sighted in the bay in the early 2000s then disappeared around 2007. “In 2017, I offered a program looking for them, and they were here.”
Ramos said that up until then, grunion had only been recorded breeding as far north as San Luis Obispo. Ramos said the fish wait until cover of darkness and the peak of high tide, before coming ashore with waves that wash high onto the beach. There, the female twists and wriggles tail-first into the sand until only her head is exposed, before laying her eggs. Males wrap themselves around her and fertilize her eggs.
“But then females and males swim back into the water on the next wave,” Ramos says.
Since grunion runs are based on lunar and tidal patterns, they tend to happen at midnight in the Bay Area, when the parks system is closed, so East Bay Regional Parks offers public viewing opportunities in May, June, July, and August.
“We’ve seen them in pretty good numbers in the past two to three years,” Ramos said, noting that Bay Area grunion are smaller than SoCal counterparts and the peak breeding season is in June, compared to April/May in SoCal. “It’s because the water in the bay is a little colder,” Ramos said.
Photo Steve Howard, iStock
Tarantulas Mating
Where: Black Diamond Mines Regional Park, Mount Diablo State Park, Sunol Regional Park, Mount Hamilton, Morgan Territory Regional Preserve, Del Valle Regional Park
When: September through October.
If you go hiking the hills in fall, you could be in for a big surprise: hairy tarantulas. But don’t worry. These giant spiders aren’t looking for you. They’re searching for mates.
As East Bay Regional Park naturalist Eddie Willis explained, “We have a tarantula season from late August through early November.”
Males emerge and wander the landscape, hunting for female burrows, where they get the female’s attention by tapping the top of her burrow’s silk lining, Willis said. The male uses special hooks to hold the female’s fangs back during mating, but even so, this spider Valentine’s season can end abruptly: “If the male has mated before and/or is tired, he could become a meal,” he said.
But maybe even that is romantic, Willis added, since once the males have mated, they are doomed to wander until they die. “They can mate multiple times, before they expire,” he continued, noting that breeding males live off stored energy reserves.
Up until then, they live in burrows that provide moisture, a cool atmosphere, and the ability to ambush passing crickets and grasshoppers. But as soon as the males emerge, which happens when they are 7 to 8 years old, their clocks are running, compared to the females, which can live to 25 years.
“Tarantulas inspire fear because of their size, but they are gentle and very docile,” Willis said, noting that their bite is no worse than a bee sting. “It doesn’t feel great, but it won’t make your hand fall off,” he said.
Still, he recommends keeping your distance. “Tarantulas have limited eyesight,” he said. “So if you get too close, they might rear up and flick the barbs on their abdomen.”
Photo Natalie Ruffing, iStock
Prairie Falcons Breeding
Where: Diablo foothills, Black Diamond Mines Regional Preserve, Morgan Territory Regional Preserve, Round Valley Regional Preserve
When: February through July.
Most people have heard of peregrine falcons, including the fact that they are believed to be the fastest bird on Earth, when they plunge to catch their prey. But prairie falcons are another story.
These beautiful large birds, which are sandy brown above and pale bluff below, have mastered a different hunting technique that is perfectly suited to the open habitat, where they live, and East Bay Regional Park staff members have reported seeing a lot of raptors, including prairie falcons and golden eagles, on the eastern side of Mount Diablo in spring.
“It’s partly because of the open country and partly because of the abundance of ground squirrels,” said East Bay Regional Park naturalist Kevin Dixon. “Out here in the rolling hills is the perfect area to come in low, at 20 feet above the ground, but really fast, so even ground squirrels, which keep lookouts, are surprised,” he said.
Nesting prairie falcons favor hollows in sandstone cliffs in the Diablo foothills and around Black Diamond Mines Regional Preserve. During breeding season, the East Bay Regional Park system closes trails that run near these sites.
So, how can the public help? Refrain from using rodenticides, since they can kill birds that eat rodents that have already been poisoned. “It’s a horrible slow death,” Dixon said.
Another way to help is to purchase land.
“We’ve been lucky in the East Bay to have been able to acquire property in the last 10 years to expand their range,” Dixon said. “It’s not just mountain lions but also raptors that need enough territory to hunt; otherwise they will be gone.”
Photo Tom Koermer, USFWS
Bats Feasting
Where: Black Diamond Regional Preserve, Big Break Regional Shoreline, Sunol Regional Wilderness
When: Spring and summer
There are 13 to 15 species of bats in the East Bay, but you need to be out at dusk to glimpse them in action, said East Bay Regional Park naturalist Cat Taylor, noting that bats use a dozen publicly accessible structures at Sunol Regional Wilderness, Black Diamond, and Big Break, with each structure housing 200 to 300 bats.
Taylor said your best chance of seeing bats is to look toward the sun as it sets, as the bats emerge from their roost.
“It illuminates the water, and you should be able to see bats feeding furiously on insects as they fly over the water for about 20 minutes, after which they go hang upside down to digest it all,” said Taylor, who recommends going on a full moon.
Her advice: Give these bats space, since these are maternity colonies, where the mothers band together for protection and warmth.
“Don’t throw rocks or shout at the bat house,” she said.
Taylor noted that all California bats are insectivores. “Out of thousands of species of bat, only three drink blood, and they don’t live here,” she said.
So far, a fungus that is devastating to bats has made its way from the East Coast to Washington state but has yet to be detected in California. Still, Taylor is worried about its spread.
“The good news is there are more reservoirs here now, which means more insect life at dusk, and there are lots of fresh water lakes, which is the first thing bats drink when they emerge at might.”
But pesticide use and wind farms are problems. “People have discovered that these huge spinning blades cause a marked drop in air pressure, giving bats what’s known as barotrauma,” Taylor said.
Ways to help? Avoid pesticides, garden organically, and install bat houses.
Photo Pixnio
Swallows Building Mud Nests
Where: Anthony Chabot Equestrian Center, Oakland
When: March through August.
Each March, folks await the return of the swallows from their overwintering places as an early herald of spring. Recognizable by their fluid wing beats, these fast-flying birds feed almost exclusively in flight, catching insects midair, as they hunt over streams, shorelines, and waterways.
Here in the East Bay, the Anthony Chabot Equestrian Center is a great place to see these amazing little birds and their famous mud nests. Perched on a ridgeline with gorgeous views of the surrounding regional park, the equestrian center includes a wooden horse barn and rafters where the swallows love to nest.
Sandy Churchill, who started working as an East Bay Parks trail guide in 1968 and now helps out at the equestrian center, said the swallows build shell and beehive-shaped nests, using wet mud they gather from creeks and streams.
“But during the drought years, some nests fell from the rafters, because there was not enough water and they were too dried out to stay in place,” Churchill said, noting that, this year, the swallows appear to be back in force.
They’re not alone. Bats also love to roost in the barn’s rafters, though they prefer spots deeper within the cavernous wooden structure.
“The matriarchal colony is on the right, with the males on the left side of the barn,” Churchill said, pointing to the inside of the barn, as a horse trainer exercised a chestnut mare. By day, the bats are, of course, sleeping.
“But they all fly out together at sunset,” Churchill said, noting the barn is open at dusk, so visitors can gather outside to observe the exodus.
Photo 27527-2 CC
Ospreys Nesting
Where: Whirley Crane, Port of Richmond
When: Spring through summer
Rosie the Osprey has one of the best views of the Bay. Perched on her nest, atop the Whirley Crane, a decommissioned World War II-era crane that stands next to the SS Red Oak Victory ship in Richmond’s Rosie the Riveter WW II National Home Front National Historical Park, Rosie can see the azure skies, the wrinkled waters of the bay—and anything that moves.
Visitors to the SS Red Oak Victory can pay $10 to access this historical ship and climb four flights of stairs, at which point, they may catch a glimpse of Rosie — or her mate, Richmond, atop a large stick nest, about 100 feet away.
Golden Gate Audubon executive director Cindy Margulis said this is the eighth year ospreys have nested atop the crane: In 2017, Rosie laid three eggs, but only two hatched and the older chick had a calamitous accident just days after hatching and couldn’t be saved.
“But the younger fledgling Rivet did survive and she wears a blue band with an alpha-numeric code on it,” Margulis said.
Last year, all three eggs hatched, and this season, Rosie, who has a brown necklace of feathers and is bigger than Richmond, is sitting on three eggs that are expected to hatch in May.
Alternatively, the curious can access the live streaming webcam that Golden Gate Audubon launched in 2017, SFBayOspreys.org, and observe Rosie and Richmond building their nest, incubating eggs, and hatching chicks — without ruffling their feathers.
Threatened by DDT in the 1960s, the osprey population recovered once the chemical was banned. But though adult ospreys have long been sighted around the Bay Area during migration or winter, they weren’t recorded nesting in the Bay Area until recent years — a development biologists believe may be linked to water clarity and wetland improvements, including eelgrass plantings that have decreased historic hydraulic mining sediment and augmented the spawning and nursery habitat needed for key fish species in the bay.
“This combination has made the bay itself a more viable place for ospreys to nest and to be able to see and find the fish they need to feed their families here,” Margulis said.
Photo Audubon Osprey Camx
Harbor Seals Nursing Pups
Where: Encinal Boat Ramp, Alameda Island
When: Winter through spring
Pacific harbor seals are the only marine mammal that breeds and gives birth in the San Francisco Bay — and there’s a whole bunch of these doe-eyed wonders lolling about on a human-made float off the Alameda shoreline, with regulars recognizable in the growing crowd.
“Once they start using a certain site, they tend to like it and keep returning,” said Alameda environmentalist Richard Bangert, noting that seals need to haul out to stay warm, but that haul-out numbers peak in December and January.
“We suspect it’s because this period coincides with the herring run,” Bangert said, adding that the water near Crown Beach and Crab Cove contains eelgrass beds, which support many species of invertebrates and fish. “Typically eel grass is good spawning ground for California Pacific herrings, so that’s our theory,” he said.
This past winter Bangert recorded 99 seals in the harbor, with more than 77 on the human-made float, but by April, those numbers shrunk to 20 to 30 seals.
“As we get closer to summer, the seals tend to leave early in the morning, maybe because the fishing is better and the water temperature is warmer, so they don’t have to haul out so much to regulate their body temperature,” he said. Since the float is anchored offshore, it’s safe to observe the seals from the Alameda shoreline, but Bangert cautioned against flying drones or paddling or rowing near these easily spooked creatures. “The main thing is to stay between the harbor breakwater and the seals, and don’t paddle directly at the float,” he said. “We don’t want anyone to test the limits, but if you are in a paddleboat, kayak, or outrigger canoe, and the seals all raise their heads, you are too close, and they’ll likely flush into water within 50 seconds.”
Photo by Dave Strauss
California Least Terns Ball
Where: Alameda National Wildlife Refuge (formerly the Alameda Naval Air Station)
When: April through August
Every year, a colony of endangered California least terns nests on an open area near runways on the now closed Alameda Naval Air Station. The area is usually off limits, but once a year, the public can take a biologist-guided bus tour to the edge of the colony to provide insights to the challenges these tiny birds face as they find mates, protect their eggs, and raise their young. Registration is required through the East Bay Regional Park District for this event, which is popular with birders and photographers, and sells out.
Leora Feeney of Friends of the Alameda Wildlife Refuge and Golden Gate Audubon Society, said these tours offer a very special experience, including an illustrated talk about least tern natural history. Tern behaviors include courtship, incubating eggs, feeding young, and maybe even a few fledglings.
Courting males will be seen with fish trying to lure females, Feeney said. “He holds his head high waving the fish, and if she’s interested, they will ‘parade’ in a circle both with heads held high.
The birds also have spectacular courtship flights called “aerial glides” where they fly very close and fast. Feeney said both of these courtship behaviors test skills needed to raise a family: good fishing abilities and swift, agile flight to escape aerial predators, especially falcons. Peregrine falcons nest nearby and are frequent visitors to the colony.
“Monitors can tell by tern behavior if a falcon is approaching as adults and skilled fledglings quickly rise upward to form a dense cluster hoping to escape the heavier falcon’s pursuit,” Feeney said, noting that crows and ravens have been a problem eating eggs and chicks. “But hanging corvid decoys at the colony has deterred them.”
Register at EBParks.org for the June 15 Return of the Tern. There are three tour times.
Photo iStock
Western Monarchs Overwintering
Where: Lake Merritt, Oakland, and Ardenwood Farm, San Leandro
When: December to mid-February.
Unfortunately, it wasn’t easy finding Western Monarchs in the Bay Area last winter — and the situation may get worse, warned Xerces Society biologist Mia Monroe.
“Their population is in decline, and it’s been going on for years,” said Monroe, who in 1997 started the Western Monarch Thanksgiving Count with two fellow biologists as a way to document and share information about the butterflies. Fast-forward to fall 2018, and the annual count showed populations at a record low.
“We think it’s a combination of weather conditions, including climate change and extreme weather, events, and habitat loss due to development,” Monroe said, noting that most of the milkweed meadows that monarchs once laid eggs and feasted on are gone. She said she believes that habitat loss combined with high pesticide use and overwintering sites that are not well managed contributed to the butterfly decline.
“It’s a statewide problem,” Monroe said, noting that there were very reduced numbers at the Gardens at Lake Merritt in Oakland and Ardenwood Farm in San Leandro in winter 2018.
Hope is not lost. Monroe encouraged people to plant native milkweed and create pollinator gardens of nectar-rich plants. She also recommended checking the Xerces Society’s Save Western Monarchs website, Xerces.org/save-western-monarchs, which posts sightings and cluster status, once the butterflies start arriving in fall.
“We’ve seen amazing recoveries in declining population of pelicans, gray whales, and elephant seals,” Monroe said. “So, we have to say, the world is in trouble, because it is, but we also have to point to the good and hopeful stories. And what we hope for the monarchs is that people become aware and choose a path of action and start seeing nature differently” Monroe said. “Now when I see a leaf munched, I say, oh, good, a caterpillar must be somewhere near.”
Photo Steve Corey CC
