Pine cones make excellent toys for birds. When collecting pine cones, ensure that they are not old, damp, moldy or are growing moss. Ideally one should collect pine cones as soon as possible after they have fallen to the ground and before they have become wet from rain. This is not always possible. Pine cones are also a favorite hiding spot for little beasts such as spiders and earwigs.
It is not possible to "sterilize" pine cones but heating in an oven will kill molds and little critters and make them safe for the birds to chew on. I heat pine cones in an oven for about 20 minutes at 225 degrees F, then turn off the oven. The pine cones are left in the oven for approx. 2 hours to dry out. It is important not to exceed 225 degrees F. otherwise the pine cones will scorch and possibly catch on fire.
The seeds inside the cones are a special treat and are safe for the birds to eat.