Perhaps they did not want to post before it happened in case it didnt happen - err - like it didnt.
Now having got myself thoroughly confused, the way I read it in the latest report was that the bridge opening was initially a trial to make sure it would work for the boat removal.
I am not sure the nesting birds theory holds water, after all if the bridge were lifting on a more regular basis, then the birds that tried to nest would just have to take their chances, though I guess if there was a nest and the chicks had just hatched, it would be nice to think they would wait a short time until they had fledged.