Ferrets 2012 Calendar. This square wall calendar features the much loved and domesticated mammal the Ferret! This wall calendar captures these beautiful pets which typically have brown, black, white, or mixed fur and measure an average length of 20 inches including a 5 inch tail, weigh about 1.5–4 pounds and have a natural lifespan of between 7 to 10 years. Each month features stunning photography in domestic settings adding a human touch to these inquisitive mammals. The calendar features full sized calendar grids each month and will make an excellent gift idea for ferret fans!