Beehives are not close to power supplies & network. would be nice to get something autonomous for power with local data transmissions .

related environmental quantities: Light (brightness, direction), temperature, humidity 

bee hive action: sound level, mass and its distribution,

inbound / outbound traffic + pollen intake (a machine vision job), perhaps microwave absorption to determine water content?

Mass and distribution of mass are the holy grail of hive monitoring. There doesn't seem to be a load cell at reasonable cost that can handle a 100% duty factor in varying environmental conditions. But if you knew the hive weight and could monitor it's changes over time, you'd be able to make better hive management decisions.

you sir gave me the craziest science project idea of the year! Stay tuned, either I'll pick it up in the upcoming 3-4 weeks or I'll write up the outline and set it free.