Nice, as usual, Charlie. Do they give numbers that reflect the # of races (one kind of status), say give you #28, maybe with a letter --- if low numbers have other 'coveted' competition?
I believe Sharon Crawford's # was eventually retired at the Canadian Ski Marathon.
When you finish the Birkie, you get a pin that has your completed number on it.
You also wear a different colored bib ( purple) that reflects that you did 20 and a member of the birch leggings club. 30 you get a gold bib ( Uberleggings)
35 you get a red bib.
My friend Joe Senal and orienteer has done 39 birkies more!