Is a video real that shows a biker on a snowy path being attacked by a mountain lion and falling off the mountain? No, that's not true: Two different online detection tools rated the video as very likely generated by AI. In reality, deadly mountain lion attacks are incredibly rare, with only 29 reported cases since 1868 according to the Mountain Lion Foundation.
The claim appeared in a March 18, 2026, video posted on X account @SineQuotes (archived here). It said:
You won't believe how this mountain lion reacted to his bike 😳🚴♂️
This unexpected encounter with a mountain lion and a bike is insane 😱🚴♂️
(Image source: post by @SineQuotes on X.com.)
Lead Stories entered the video into the Hive Moderation AI-Generated Content Detection tool, which concluded the video was "likely to be AI-Generated" with an aggregated score of 100 percent. The higher the score, the greater the AI content. Here is a screenshot of the results:
(Image source: screenshot of Hive Moderation website.)
Lead Stories also ran the video through Gemini, Google's AI assistant. It reached these conclusions:
This video is widely regarded as a fake, likely created using a combination of CGI (Computer-Generated Imagery) and clever editing, rather than being a single real-life event.
While the SynthID tool did not detect a Google AI watermark, there are several visual and contextual reasons why this clip is considered fabricated.
Key Evidence
Inconsistent Physics: The way the mountain lion lunges and the subsequent fall of the biker appear 'weightless' or floaty, which is common in low-to-mid-budget CGI. The cat's movements do not realistically interact with the snow or the bike.
Video Origin: This specific clip has circulated on social media platforms like TikTok and X (formerly Twitter) with titles suggesting it's a 'lost footage' or a 'terrifying encounter,' but there are no verified news reports of such a dramatic event. Real mountain lion attacks on bikers are extremely rare and almost never involve a biker falling off a massive cliff while filming.
Editing Cues: The video uses common 'found footage' tropes, such as high-pitched screaming and chaotic camera shaking, to mask the imperfections of the digital effects.
Had such an attack been recorded it would have been on the internet and likely news outlets would have picked it up. Lead Stories searched Google news (archived here) and Yahoo (archived here) and did not find any reports or videos that matched the one in the post.
The Mounain Lion Foundation reviewed the scientific literature concerning mountain lion attacks on humans and found them to be "incredibly rare" (archived here):
In spite of their rarity, each story of a mountain lion attack can incite fear, often quickly followed by a flurry of ill-informed plans to prevent such attacks. There have been 29 cases (not all confirmed) of fatal mountain lion attacks on humans in North America since 1868, for an average of about 0.18 attacks per year.
