The Bottle Bird House - this style is an adaptation of a traditional English terra-cotta bird house. It is made of earthenware and is fired to 1860 degrees Fahrenheit for durability, and it is stained rich-brown, resembling bark. It cannot be enlarged by squirrels, and remember that the entrance hole should be pointed away from prevailing summer winds. The house should be cleaned every fall, but be sure to leave a little of the nesting material to welcome the next season's guests. It is available in three sizes.