A milk carton might seem like just another piece of trash, but to a bird it can be a snug house if it is used properly. A milk carton bird house is an easy, inexpensive recycling project that the birds will appreciate, and birders of all ages can turn an empty carton into a backyard bird condo.
Choose Your Carton
Any paper carton can be used to create a recycled bird house, though a half gallon or larger size is best – smaller, individual cartons will not provide adequate space and hatchlings in larger broods could smother. The carton may be from milk, juice, soup broth or other liquids, and it may have a foldable spout or a screw cap for pouring. No matter what the type of carton, it should be in good condition after it is empty, and sturdy enough to withstand birds' use and local weather for several weeks.
Prepare the Carton
Before creating a bird house from a milk carton, the carton should be thoroughly cleaned. Empty any remaining liquid and rinse the carton with hot, soapy water, then again with clear, fresh water. A final rinse with a weak chlorine bleach solution can further sterilize the carton and remove odors that may attract predators. After washing, allow the carton to completely dry to avoid any mold or mildew.
Once the carton is dry, staple or glue the foldable spout closed or be sure the screw top is firmly attached. Use an awl or large nail to add ventilation holes at the top of the carton – 2-3 holes should be placed at each end under the overhang of the folded top. That overhang will help keep rain from getting into the ventilation holes while still allowing air to circulate for a safer, healthier bird house. Drainage holes should also be added to the bottom of the carton – one in each corner, about half an inch from the edge of the carton. This will help with additional circulation and keep the birds comfortable, and any accumulated water or feces will be better able to drain away.
Next, carefully cut an entrance hole on one side of the carton, using scissors or a knife. The hole should be centered horizontally in the side of the carton, and positioned 3-4 inches above the base. A higher hole will be too difficult for hatchlings to exit, while a lower hole could endanger young birds that may fall from the opening. Birders who hope to have specific birds use the house should create a hole with the proper entrance size for the species, otherwise a 1.5-inch hole will be suitable for many backyard species.
The carton can be decorated if desired. Paint the bird house with non-toxic paint, or use non-toxic glue to attach twigs to form a roof, or leaves, moss and other natural materials to disguise the carton. Construction paper can be glued to the house, or stickers or similar materials are great decorations, but do not obstruct the ventilation or drainage holes with decorative materials.
It is important to note that no perch is necessary for any bird house. Birds do not need a perch to access the house, but predators will use one as a grip while they raid the house for eggs or young birds. For the look of a perch without the danger, use a small stub of a branch or twig – less than an inch long – attached below the entrance hole, but avoid a longer perch that could be harmful to the birds.
Mounting the House
Hanging a milk carton bird house is easy. Use twine or string, and thread it through two ventilation holes on opposite sides to provide secure, sturdy support with a minimum of swinging. If desired, use more than one loop of string or twine to secure the house, but be sure they are the same length so the house is not unbalanced. The house should be hung in a shady, protected area with a good supply of nesting material nearby to entice birds to take up residence.
Cleaning a Milk Carton Bird House
All bird houses should be cleaned after the fledglings leave so there is no remaining bacteria to infect the next nest, and even unused houses should be checked and cleaned to remove mites, insects, rodents or other infestations. Fortunately, a milk carton bird house is easy to clean – it can simply be discarded! Depending on any decorative materials, the house may be able to be composted or recycled as appropriate. It is not wise to reuse these houses for multiple nesting seasons because the paper of the carton will gradually begin to decay, but because they are so easy to make, it's never a problem to simply create a new bird house for the next family to enjoy.
Photo – Juice Cartons © Carl