http://www.moonpage.com/ To find the phase of the moon when you hunt.
Hand held Anemometer for measuring wind speed and temperature. 
MP3 Voice recorder for note taking and recording observations. 
Microsoft Excel Spread Sheet for some recording of data and calculations. 
Microsoft Access for the storage of data for later analysis. 
A sharp knife for inspecting stomach contents. 
A hand held GPS marks the position of each fox or cat. Also measures distance traveled. 
Digital Fish Weighing Scales for quickly and accurately weighing foxes and cats. 
Counter for Foxes Shot tally. 
Counter for Foxes Seen tally.
With these few simple tools, approximately 22 items of data can be collected for later analysis.