When you say bucks are you saying big mature bucks like 8's - 10's - 12's or young spikes, fork horns, 6's. Young bucks will chase anything they feel more dominate than even before the rut. A lot of times they will bachelor up 2-4 with other bucks just before the rut. Then in pre-rut they go off and start scraping and setting up their territory. I’ve watched bucks chasing doe’s in the middle of the summer (in velvet) as more of a playful activity.