The best I could find is that there are an estimated ~20 billion birds in the US, and there are an estimated ~5 million multi-rotors. What I don't know is whether these numbers count the tiny 'copters that people fly indoors or around their yards, or how many are no longer in service. It's based on sales figures from reported sources. The bird number is a quasi-scientific estimate that I have read from several sources.
While 'copters might not have very good situational awareness, the vast majority of their flying is done in limited areas, where aviation is not generally done. Birds, usually displaying situational awareness, are nevertheless not limited in any practical way in their flight, other than what nature does species by species.
I don't fly gliders (yet), so I can't attest to bird interactions with gliders at 45-65 kts near thermals or whatever, but I have seen numerous eagles, hawks, geese and multitudes of shorebirds at various times while flying. Even as a passenger, I'm the guy who loves the window and looks out the entire flight, so I notice quite a variety of "air traffic". In fact, just the other day, I was flying to Southern California enjoying the view of a thunderstorm north of us in Arizona when I saw a meteor. Noticed it right away as it brightened and streaked downward. It seemed greenish and right about the time it got somewhere between the thunderhead and our plane, it broke in two visible pieces, flared and went dark. I was surprised to see one penetrate so deeply into the atmosphere. It was lit up well below the level of the plane, and it passed between us and the thunderstorm, so it was less than 30 miles away and probably much less.
According to NASA, 100 tons of material falls into the atmosphere daily, and a fraction reaches earth. In 2014, a wingsuit skydiver was almost struck by a falling meteor (captured with his camera).
Interesting stuff to say the least.
Not meaning to be pedantic, but the $80 Billion market for commercial drones makes up a lot more than the purchase price of the aircraft. This means you can't divide the market up by a cost, and expect to yield solid numbers. The Market includes R&D, consulting, associated overhead costs, marketing, lending, real estate, service and parts, intellectual property, profit etc, in addition to actual multi-rotor sales.