Sometimes hole-nesting birds will make their nests in uncapped vents, holes in roofs, or other crevices around building. European starlings and house sparrows are the usual culprits. Remember that birds only use holes like these when they are nesting, so always assume that there are babies inside.
Be patient with nesting birds
The nesting season for songbirds is very short. Most baby birds leave the nest when they are only 14-21 days old! Once they leave the nest, they don’t go back again—birds only use nests to raise their babies in. When the babies leave, the nest can be cleaned up and the entry point sealed up to prevent future nesting.
Since nesting birds don’t usually cause any damage or pose any danger, we recommend waiting the short 2-3 weeks until the babies have left the nest on their own.