Gray bats leaving their roost
During the spring months, most species of bats will be transitioning from their wintering sites to their summer sites to establish maternity and bachelor colonies. The pregnant females will usually go to the same area where they were born to have their young. Sometimes these areas can be man-made structures such houses, attics, barns, or garages. These bats will also roost under window shutters and behind gutters, any place that provides privacy, protection, and warmth for them so they can raise their young.
The summer months (late May to July) are when baby bats, called pups, are being born. This is a time of year when you may start to see bats on the ground or in your house. Not all baby bats survive, unfortunately. Mid to late July is typically when they learn to fly, or become volant. They are like teenagers first learning to drive. They often end up in your house or garage as they can take wrong turns testing out their wings. The best thing to do is to keep all pets and children away from them as they typically will take off again when they have rested. However, if you see what appears to be an apparent injury, please refer to the list of wildlife rehabilitators.
During the fall months, the opposite occurs. Bats will be leaving their summer areas to migrate back to their wintering areas, which can be caves or warmer climates just like birds. During this time, bats can become confused and tired and will find a place to rest, sometimes in our houses, garages, or even on the sides of buildings. The best thing to do is to leave them alone and keep children and pets away.