The motor should be a 7 RPM constant speed motor, like an AC synchronous motor. These motors are sometimes called synchronous gear motors. They are typically small and very quiet.
The motor must be able to handle at least 2x the torque required to drive Colibri. More torque is even better.
The motor should mount to the Support Frame part, not to the Base. By mounting to the Support Frame, the motor will move with the Frame and the hummingbird. If it is mounted to the Base, the timing of the mechanisms can be affected, leading to a more unnatural motion.