How to take a picture like this?

Solutions:

• Take a picture every N seconds and delete the ones without a Hummingbird
• Use an ultrasonic rangefinder to detect the bird and take a picture
• Take picture and compare to one without a bird and save if significant deltas
• PIR sensor
• Security camera and record all the time.  Save single frames with birds in them.
• Vibration sensor on feeder. (Hummingbirds are quite light.  Might not be sensitive enough.  Or too many false positives from wind)
• Listen for wing beats (it is a distinctive sound)
• gPhoto 2 running on Linux can control camera and send pictures for delta comparison.

A month or two later, Robert Henry brought in a camera with a PIR sensor and control software on an Arduino that takes three shots when the PIR sensor is triggered.  Don’t know if it will detect hummingbirds, but catching his kids moving around works.