Moose are HUGE!
...with appetite to match, I'm sure.
Are you sure the Juncos are eating the petals and not seeds?
The come to my garden with the arrival of hard frost/freeze and stay until just before and/or as the Robins return from their sojourn in the South. They do a thorough job of cleaning up a lot of the weed seeds and flower seeds during their stay.
Also, since in your case, the Junco's are probably nesting, it's possible they are finding bugs -- typical one might be those worms that seem to like marigold/daisy type flowers -- to feed their young? Very curious....