Answer 7_5_3
The hot reservoir is the air in the room.
The cold reservoir is the cooling effect of the evaporation of the water on the beak.
(The latent heat of vaporisation of the water as it evaporates cools the beak down and the heat of the room causes the red alcohol to evaporate. The pressure at the bottom causes the fluid to move up the tube and tips the duck forward. When it's forward the fluid runs back down again, making the duck move into an upright position.)