What kind of hardware is required to monitor eating habits of squirrels?
That's a tough question, a lot of practicable solutions are coming into my mind. Nowadays a wide range of sensors and micro-computer platforms are available to choose from.
I opted for a 1st generation Raspberry Pi which I've bought many moons ago. The credit-card sized Raspberry Pi is a great environment to easily try out some "IoT" (Internet of Things) prototyping with sensors attached.
Currently a mercury switch, a temperature sensor and a dual-color LED which is used as a status light are attached to the Raspberry Pi's GPIOs.
The mercury switch is mounted on the feeder's lid. In order to give a visual feedback that the lid has been opened the status light changes from a pulsating red to a static green. Whenever the lid has been opened the current temperature is being read from a DS18B20 sensor and the IoT Squirrel Feeder starts tweeting.
Currently I'm using sensors which are produced by SunFounder, a UK based company. You can buy SunFounder's sensors at Amazon:
If you don't own a Raspberry Pi yet you can order one at Amazon, too:
I've added a ESP8266 based Witty Cloud board to read and publish weather data independently from the Raspberry Pi which is attached to the feeder. A Light Level sensor is onboard. A DHT22 has been added to read temps and humidity.
* - Amazon Affiliate Links