If you have bats in your attic, you might notice them flying out of your attic at dusk. Observe from a distance!
Position yourself at a vantage point where you can see the roofline against the fading light of dusk. Bats typically exit their roost 15 to 30 minutes after sunset to forage. Conversely, at dawn, they return to the roost. Look for small, erratic silhouettes swirling around chimneys, gable vents, or loose fascia boards.
Look for small openings around your roofline, eaves, vents, or chimney. Bats can squeeze through gaps as small as 3/8 of an inch.
Watch Bats Leaving Attics
Video from Houston and The Woodlands.