I solely use White Flyer Biodegradable Pigeons. When I hear the word Biodegradable, I think of the Bill Engvall camping comedy skit where he talks about “rapidly dissolving toilet paper” .
In my experience, they do not dissolve as fast as I would like, but they will eventually mostly dissolve. In my field, it can take 2-3 years for them to go away. I have not noticed a difference in flight or break-ability of them.