> In more developed areas, there are three options. Fast (main road for cars), medium (bike lane) and slow (sidewalks). I'd imagine birds would ride in the medium and slow lanes.

And to be clear 'bike lane' != road shoulder with a bike painted on it. A bike lane should have at least some amount of separation from the road in the same way that sidewalks are separated.

I'm hopeful that the popularity of scooters speeds up the adoption of medium speed lanes.