I have built a bird box that's currently in a tree at Murray Edwards College with a built-in Raspberry Pi to log light, temperature, entry/exit detection and photos to another server (sftp upload) and Twitter. All data is stored in a sqlite database with a view of analyzing this data at a latter date.
The circuit is very simple, I have used MCP3008 AtoD chip connected to the Raspberry Pi using the SPI interface. Using three channels on the MCP3008 I have connected two IR transistors and a light dependent resistor as a voltage divider. The temperature sensor is connected using '1-wire'. Full details on how to set up your pi can be found on the Internet see here for the temperature sensor and here for the AtoD/
My code can be found here https://code.google.com/p/pie-bird-box/
The box can be followed
