The wings are maybe a bit dark, but otherwise this fits the description pretty well:

Bearback, I was up in Telegraph Cove on Vancouver Island a few years ago, we followed a forestry trail and found a big area where they mulch bark and fish heads.

Didn’t didn’t get very far counting on the mounds of mulch, in the air and in the trees surrounding. It wasn’t long before we were gave up with a mix of awe and profanities.

I don’t think “hundreds” would be an exagqeration at all. Pretty intimidating, actually! There were four of us, but if they’d wanted to…