INCLINE VILLAGE, Nev. – 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., and despite the unfortunate demise of the bird, its widespread documentation and discussion highlights the importance of citizen science, the Tahoe Institute of Natural Science (TINS) said.
The Cocos Booby was first spotted fishing in the Tahoe Keys area on August 1st, and a photo of the bird was posted to the 3,200-member Tahoe Birding Facebook page, with a caption asking “Saw him flying at Keys Beach today, any idea what kind he is?” The page is administered by TINS, and Sarah Hockensmith, TINS Outreach Director, immediately recognized the photo as a booby. Over the next eight days, untold numbers of birders made the trip to Lake Tahoe to watch and photograph the large bird’s magnificent aerial acrobatics and cartwheeling dives as it fed on small baitfish, said Will Richardson, executive director Tahoe Institute of Natural Science. Most of the birders came from within a day’s drive of Tahoe, but one couple traveled 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.”
While boobies and other birds are often blown well out of their typical habitats during big storms, the bird’s appearance in South Lake Tahoe was slightly baffling because weather patterns were perfectly clear.
“For whatever reason, this booby decided to fly up and over the Sierra Nevada. It’s just mind-boggling,” Richardson said. “That’s precisely how we get range expansions, and it’s a good sign of adaptation. Conditions on the planet are changing, and seeing birds pushing the boundaries of where they are trying to live shows how they are able to adapt and shift their ranges. It’s sad when birds end up in a place where they can’t live, but overall, it’s a sign of nature’s perseverance.”
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 fresh-water baitfish. The bird was found dead on a boat at Ski Run Marina late on August 9th, 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.
“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.”
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.”
About TINS
Founded in 2010, the Tahoe Institute for Natural Science (TINS) is a member-supported nonprofit organization providing world-class education and research. TINS offers programs for all ages, from presentations to citizen science projects to guided nature outings. Scholarships and a diversity of free programming aim to make these activities as inclusive as possible. The organization conducts ongoing biological research in the Tahoe-Sierra region, contributing important data to help improve management decisions regarding wildlife. TINS is working to bring a world-class interpretive nature center and educational facility to the Tahoe area, with the ultimate goal of creating a community that cares for the natural world by fostering a deeper understanding and appreciation of the natural resources at Lake Tahoe and beyond. For more information visit tinsweb.org.