Just a few quick and rough annotations as to things that I wish to add:
Camera Multiplexer - for more than one camera (http://www.ivmech.com/)
very much like so: https://hackaday.io/project/2847-ivport-raspberry-pi-camera-module-multiplexer, requiring https://github.com/ivmech/ivport
GPS - ok just a gimmick.... because I can for the moment - bringing birdies and space together is a thrilling idea - but mostly for the future when nesting boxes will populate the woods and scientists need the GPS position of the boxes. At any rate this is what I intend to do: https://learn.adafruit.com/downloads/pdf/adafruit-ultimate-gps-on-the-raspberry-pi.pdf
Bluetooth - ...as already mentioned before
Sensors - of various types...