SOUTH LAKE TAHOE, Calif. – The sighting of a rare Cocos Booby (a species of seabird split from the Brown Booby in late 2024) in South Lake Tahoe in August stoked tremendous excitement among nature and birding enthusiasts from across the U.S.. Despite the unfortunate demise of the bird, its widespread documentation and discussion highlight the importance of citizen science, the Tahoe Institute of Natural Science (TINS) said.
It all started when a member of the TINS 3,200-member Tahoe Birding Facebook page posted the photo of the bird, asking if anyone knew what it was. Sarah Hockensmith, the TINS outreach director, immediately recognized the photo as a booby.
The person who originally posted the photo gave it the caption, “Saw him flying at Keys Beach today, any idea what kind he is?” The Cocos Booby was first spotted fishing in the Tahoe Keys area on August 1st, and stirred up a lot of excitement in the birding community, even drawing a couple from Minnesota to see the bird.
“It is a bit insane for a booby to show up at Lake Tahoe,” Richardson said. “It’s a tropical seabird that lives on the ocean, and this species, up until 25-30 years ago, was still pretty rare to see anywhere in the state of California.”
Climate change, warming ocean currents, and redistributions of its prey base led to numerous Brown/Cocos Booby sightings along the coast of Southern California in the early 2000s, and in November of 2017, biologists at Channel Islands National Park documented 102 boobies and four nests on a rocky islet near Santa Barbara Island.
“That’s huge to go from super rare to nesting in colonies in a period of 10-15 years,” Richardson said. “And they continue to expand their range and become more numerous.”
Richardson said one showed up in West Yosemite in 2020, but he said that was “absurd as well, but this one made it up and over the mountains.”
“It is completely unprecedented for one to show up in Lake Tahoe,” said Richardson. “An extraordinary one. This is an ocean bird that needs salt water.”
The booby spent the week fishing around the Tahoe Keys and putting on quite the show for those wanting to photograph it.
Although it was feeding well, the Lake Tahoe Cocos Booby was up against formidable dietary challenges, which likely led to its unfortunate demise. The booby’s physiology and internal chemistry have evolved to process large amounts of salt, which is lacking in freshwater baitfish. The bird was found dead on a boat at Ski Run Marina late on August 9, after being seen fishing earlier that morning, and being witnessed making a long, high flight towards the west at sunset the previous evening.
Staff at the marina were holding the specimen for TINS, but unfortunately, the carcass was claimed by an unauthorized party and has disappeared, so the specimen isn’t available for scientific study and documentation. It is a violation of the Migratory Bird Treaty Act to remove a bird without authorization.
“With a tissue sample, we would be able to determine its species definitively, which would be very useful to be able to know the distribution patterns of these birds as they expand,” Richardson said. “This was a juvenile bird that may possibly have come up from the Gulf of Mexico (making it a Brown Booby), but we can’t determine that at this time. If we had the specimen, we also would be able to determine its stomach contents and perhaps confirm how and why it died.”
Richardson said, if someone were to return the carcass, it’s not too late to study it. If anyone has information, please contact him at will@tinsweb.org.
Despite the disappointment of booby’s demise and disappearance, it was an extremely rare opportunity for birding enthusiasts to witness the bird outside its natural habitat. The Cocos Booby is another example of the diversity of bird species that appear in the Lake Tahoe region. More than 320 different bird species have been documented in the Lake Tahoe basin, TINS reports. Among them:
- Scissor-tailed Flycatcher, the state bird of Oklahoma
- A Western Sandpiper that was color-banded in Siberia
- Lesser Black-backed Gulls, likely breeding in Iceland
- Arctic Terns that are flying almost from pole to pole
- Other ocean-migrating species like jaegers and Sabine’s Gulls
“We are truly connected to most of the Western Hemisphere and then some with the birds that come through the Lake Tahoe area,” Richardson said.
The thorough documentation of the Cocos Booby through hundreds of stunning photos posted to the Tahoe Birding Facebook group also underscores the importance and impact of citizen science in advancing the goals and mission of Tahoe Institute of Natural Science.
“Any wildlife observation can be very important and impactful and possibly lead to major discoveries or even policy changes,” Richardson said. “In the aggregate, all those entries equals important data that allows us to track range expansion, changes, contractions, or declines in populations over time. One curious post on a Facebook group can lead to great discoveries. Everyone has a phone in their pocket with a camera, and we encourage folks to post their photos – you never know what discovery you might make.”
