Bird chirp detector

I was lying in bed the other morning listening to the birds chirping outside and I was wondering if I could build something to monitor the activity. They start around 4:30AM and trail off around sunrise.

I was thinking of a simple bandpass filter? Maybe feeding the output to a zero-crossing detector and then to a PIC?

Any thoughts?

Mike

Sounds like fun, i'd get a sample onto my pc, analyze it for anything that differs from whatever sounds are common at that time of the morning? Then maybe use a couple of filtered VOX to an AND gate to trigger my digital camera with a date stamp, that way i could see what time the noises started. Of course later i could trigger a strobe outside to scare them all off, damn flying rats