Materials

Balsa Wood (for doors and scissor perch for the bird)
Cardboard (for base and scissor pedestal)
Pins (to attach beam to the door and various other bits)
Electrical and regular tape (to attach perch to the cardboard base)
Fishing wire (as pulling mechanism for both doors and scissor)
Yellow wire and pipe cleaners to build the aerodynamic bird
Rubber bands (to open the doors but even more to slam them shut)
Pins and brads (to keep it all together)

It works fine and it's all controlled by one wire, with the additional bonus that the bird's head plumage becomes first a necklace and then a tail every time the bird jumps out of its house. 

Photos 

cuckoo clock - behind the scenes

cuckoo clock - it's noon!