He provided a place where readers could find him "in case the bird app spirals into oblivion": his Substack newsletter.
The epidemiologist Eric Feigl-Ding began promoting his Substack newsletter to his 722,000 Twitter followers in early November.
They have been a welcome addition, Substack writers say.
Substack has also recently rolled out mentions and cross-reporting functions, where writers can mention other Substack writers and share existing posts with their audiences.
The irony, of course, is that many Substack writers rely on their Twitter audiences to promote their posts.