  Open-source journalism emerged as a new phenomenon in the media ecosystem,
which uses crowdsourcing to fact-check and generate investigative reports for
world events using open sources (e.g., social media). A particularly prominent
example is Bellingcat. Bellingcat is known for its investigations on the
illegal use of chemical weapons during the Syrian war, the Russian
responsibility for downing flight MH17, the identification of the perpetrators
in the attempted murder of Alexei Navalny, and war crimes in the Russo-Ukraine
war. Crucial for this is social media in order to disseminate findings and
crowdsource fact-checks. In this work, we characterize the social media
activities at Bellingcat on Twitter. For this, we built a comprehensive dataset
of all N=24,682 tweets posted by Bellingcat on Twitter since its inception in
July 2014. Our analysis is three-fold: (1) We analyze how Bellingcat uses
Twitter to disseminate information and collect information from its follower
base. Here, we find a steady increase in both posts and replies over time,
particularly during the Russo-Ukrainian war, which is in line with the growing
importance of Bellingcat for the traditional media ecosystem. (2) We identify
characteristics of posts that are successful in eliciting user engagement. User
engagement is particularly large for posts embedding additional media items and
with a more negative sentiment. (3) We examine how the follower base has
responded to the Russian invasion of Ukraine. Here, we find that the sentiment
has become more polarized and negative. We attribute this to a ~13-fold
increase in bots interacting with the Bellingcat account. Overall, our findings
provide recommendations for how open-source journalism such as Bellingcat can
successfully operate on social media.
