<p>Small mustelids such as the European polecat (<i>Mustela putorius</i>) and the least weasel (<i>Mustela nivalis</i>) are elusive species consistently underrepresented in ecological research, with persistent knowledge gaps regarding their behavior, distribution, and conservation status. Monitoring these species poses considerable challenges due to their cryptic habits, low detectability, and the limited effectiveness of conventional methods such as systematic camera trapping. The increasing use of affordable camera traps by amateur naturalists, along with the widespread dissemination of wildlife images via social media, offers an emerging and largely untapped source of ecological data. This study evaluates the potential of opportunistic camera trap records shared on social media to investigate diel activity patterns of polecats and weasels in Central and Northern Italy. A total of 204 timestamped images (146 for polecat, 58 for weasel) were collected and verified through direct contributor engagement to ensure metadata accuracy. Temporal patterns were analyzed using circular kernel density estimation. Polecats exhibited a marked nocturnal activity pattern, ranging from 18:00 to 08:00, with a pronounced peak around 02:00. In contrast, weasels showed predominantly diurnal behavior, with activity peaking around 9:00. Despite inherent biases associated with opportunistic data, this approach enabled the rapid, low-cost acquisition of ecologically meaningful information. These results highlight the potential of curated, citizen-generated data from social media as a scalable and cost-effective resource for studying elusive species.</p>