Time for spring cleaning. Yes, in and around your home. Also the homes of any birds you might have in your yard.
Birdhouses can become homes for mites, little spiders that infest the nest, suck blood from helpless nestlings and weaken them.
To avoid this pest from harming “your” birds, please clean out your birdhouses. Open the bird box. If possible, remove it from its site. Remove old nest material while wearing a dust mask. Flush with boiling water without any added chemicals. Let it dry overnight. If you can’t easily remove it from the pole or tree, leave it open to dry.
If this process is too difficult, at the least remove the old nest material.
Remember that destroying the nest of a migratory bird is prohibited. So if you don’t want swallows under your eaves, take preventative measures now.