This episode shows how to use a motion/distance sensor with the Camera Axe.
The sensor used is a LV-MaxSonar-EZ1 (datasheet). This sensor not only detection motion, but will give back a distance from the sensor. It measures distances from 0 to 21 ft and take about 20 readings per second. 20 Hz is more than fast enough for wildlife. Check out the data sheet for more detailed information.
I show how to setup the camera axe for basic use and then a more advanced usage case.