This is the Pseudonym which Harlan Ellison uses when he does not wish his own name to appear on a script or book because of excessive interference and changes. It is his own personal version of the Movie Director's Alan Smithee pseudonym. He has it registered as an official nom de plume with the writer's guild so it has to be used if he says so.

He uses Cordwainer, I believe, in memory of Cordwainer Smith the S.F. writing pseudonym of Paul Linebarger. Bird refers to Flipping the Bird which is what Harlan is doing to the people who messed with his story.

One particular use I believe was when he insisted that it be used on the Canadian TV Series "The Starlost" (for which he wrote the original pilot script). To get an idea of just how badly treated this was read the book "The Starcrossed" by Ben Bova (who was also involved on the project as a consultant). This is a science fictionalised version of the events and is a fun read (the character based on Harlan is ... volatile).