We have met the approval of the International Standard of Ornithology of 2012. Make sure your birdhouses are ISO 2012. Check your birdhouses to make sure they have proper hole sizes, venting, drainage, and clean-outs. Failure to meet ISO 2012 will result in the City of Berkeley(liberals with fascists tendencies) citing you for birdhousing violations. How to check to make sure your birdhouses are ISO 2012:
Ten Features Of A Good Birdhouse
There are lots of cutesy birdhouses at your local stores and garden nurseries. They don't work for birds to nest in. In fact, don't use them since they will kill the bird's young since most use toxic paint, glue, and do not have venting and cleanouts. Birds prefer rustic and natural looking birdhouses to simulate nature and camouflage as they nest. My birdhouses are guaranteed to be nested or you can get a refund.
Below is a checklist of the ten most important features of a good working birdhouse. Before you put a house out for wild birds, be sure it has these ten features. If it is decorative and still has these features, then it is fine to put it out for the birds.
1. No Perch(door knobs are ok) Tree holes in the wild have no perches, so the birds that use nest boxes do not need them. They can be a disadvantage in that they may attract House Sparrows, an invasive species that often takes over nests from our native hole-nesting birds.
2. Entrance Hole Size Most of our common hole-nesting birds can use an entrance hole 1 1/2 inches in diameter. This size also keeps out Starlings, another invasive species that takes over nest boxes from native species.
3. Floor Dimensions The inside dimensions of the box are important and should be at least 4 inches by 4 inches so that there is room for the young to develop.
4. Box Height The distance from the bottom of the entrance hole to the floor of the box should be at least 5 inches. This keeps the developing young well down in the box and away from predators that might approach the entrance hole.
5. Be Able to Open You must be able to open the box, either on the side, front, or top. This helps in two ways: to monitor the progress and health of the young; and to clean out the box at the end of the season.
6. Ventilation There must be holes or slits at the top of the box sides or along the top of the front of the box to let hot air out when the sun beats down on the box in summer.
7. Drainage Holes The bottom of the box needs to have holes or cut off corners to allow any water to drain out of the box.
8. A Way to Attach the Box Check to see if there is some way that you can attach the box to a pole, such as holes or a bracket.
9. Should Be Wood Be sure that the materials the box is made of are 3/4 inch thick wood or a similar material that will insulate the birds from cold and heat.
10. Roof Overhang The roof should overhang the entrance hole by 1 to 2 inches. This both shades the entrance hole and keeps the rain out.