Never seen in California

Mysterious bird never seen in California draws crowds to San Francisco park

By Amanda Bartlett

It was a Monday, Dominik Mosur’s usual day off from his job as the animal care specialist at the Randall Museum, when he decided to set out for an afternoon of bird watching at Pine Lake Park near his home in San Francisco. He never guessed he was about to record his rarest sighting yet.  

As he wandered through the willows, he heard the unmistakable sharp tick of a warbler’s call. He mimicked the sound himself, patiently peering through the dense vegetation, when the tiny bird suddenly popped into view.  

“I was just awestruck,” Mosur told SFGATE over the phone Monday morning. “It was like a little miracle.”

He dropped to his knees, simultaneously looking through his binoculars and taking photos with his phone. The bird’s plumage was a little raggedy, indicating that it was probably molting, though it didn’t take away from just how striking it looked — a needle-thin bill, black feathers and a bright ruby-red belly. After a few moments, it disappeared.

In that time, Mosur was able to text a few of the photos he captured to a group chat he was in with fellow birders. They confirmed his suspicion: He had found a slate-throated redstart, a species typically observed from Mexico to Central America and all the way down to Bolivia. Sporadic sightings have been recorded in Arizona, New Mexico and Texas but never once in California. 

“The fact that it showed up here in San Francisco is really cool,” Mosur said. “You can travel halfway down the continent to find this bird, or you can go to your neighborhood park, and maybe it’ll come to you.”    

Word traveled quickly. By the next morning, at least three dozen birders, some of whom had driven overnight and flown across the country, had flocked to the very spot where he stood, hoping to catch a glimpse of the rarity. All told, Mosur estimates around 150 people were there that day, and crowds are still swarming the park to watch the bird as it circles around the lake to forage, sometimes flashing its white tail feathers to surprise an unsuspecting insect and gobble it up. 

“It became this anarchy, a little bit,” Mosur said of the throngs of people. “But everybody was really jazzed. It was like a holiday.”  

How the little bird got here is tough to say. Generally, slate-throated redstarts are not migratory and therefore don’t show up in “crazy, weird places,” said Whitney Grover, deputy director of the Golden Gate Bird Alliance. Experts believe this particular individual is a subspecies from Mexico, which takes part in elevation migration, traveling between lower and higher altitudes rather than north and south, but since there are no published scientific studies about these patterns, little else is known.

“It’s really shocking to have it be so far from its normal range,” Grover said. 

Monsoonal moisture from tropical storms in northern Mexico may have thrown the bird off course, Mosur said, but he thinks that because the subspecies could be increasing in population, more individuals are potentially venturing out to explore new nesting spots. “Maybe a young bird with a wayward GPS system went too far north,” he said with a chuckle. 

Grover noted that species will also sometimes go outside their usual range as a form of “healthy and normal” exploration. 

“It’s naturally part of evolution and adaptation to find a new territory that could be advantageous for the bird and, later, the species,” Grover said. “Still, there’s no way to know, really, and it’s pretty interesting. It could be any of those things, a combination, or something else entirely.”

In the span of a week, the news has traveled far and wide, receiving national attention on the American Birding Association’s popular podcast. 

“This is a pretty significant outlier,” host Nate Swick said of the discovery. “When California adds a new species to its already quite expansive state list, it is a big deal.”

Kaleb Friend, a photographer based in Palo Alto, said he received a rare bird alert on his phone from the ABA last week and knew he had to see it for himself. 

“When I realized it was in San Francisco, a 10-minute walk from where I used to live at a park I used to go to all the time, I said, ‘This is sort of irresistible,’” Friend said. He found the vagrancy of a typically sedentary songbird and the distinctive plumage of the subspecies particularly compelling (slate-throated redstarts in northern Central America typically have orange bellies, while those of the songbirds found from Costa Rica to South America are yellow.) 

As more bird-watching enthusiasts descend on the Stern Grove-adjacent park to spot its unusual resident, Grover encourages people to be respectful: Don’t use playback, or recordings of bird calls, to attract the bird, which can agitate it or confuse other birders. She also recommended staying on trails and avoiding trampling over vegetation, “even if you want that amazing shot.” It disturbs the habitat of the bird as well as other city wildlife. 

“It’s better to hang back and plant yourself in one spot to watch it behave normally,” said Friend, who, after a few silent minutes, saw the bird open its mouth and start singing. “I was so dumbfounded, I just stopped shooting.” 

The species is typically well-adapted to forest edges and human disturbances, but Mosur still fears for the future of the lost songbird. It could get too cold by the time winter comes around or get pounced on by a predator — bird mortality rates are often high, he explained, and 50% to 90% of them don’t reach maturity, depending on the species. But because the bird is starting to shed its feathers, he hopes that it will continue to feed and molt until weather conditions improve and muster up the energy to fly back home. 

“What we’ve seen in the past with these kinds of birds is if they successfully leave where they’ve been lost, they’ll come back,” he said. “Maybe it’ll return, and it’ll be a regular thing.”