An Arduino processor provides the signals needed to drive Peltier cells which heat the fluid in the birds and causes the bobbing motion.
Construction details can be found here.
For more general information, check out this post.
The Flock Clock uses male and female drinking birds to display time.
Cute! Haven't seen those drinking birds for years. Might get hypnotised by the bobbing and end up several minutes late. 😉
Your program could be made more succinct by using bit operations on the minutes and seconds since they are binary values, i.e.:
digitalWrite(1, minute &0x1 ? HIGH : LOW);
digitalWrite(2, minute & 0x2 ? HIGH : LOW);
digitalWrite(3, minute & 0x4 ? HIGH : LOW);
digitalWrite(4, minute & 0x8 ? HIGH : LOW);
and similarly for the hours.