Complex sentence: It roosts on dead, leafless trees, and will also roost on man-made structures such as water or microwave towers though it nests in caves, it does not enter them except during the breeding season.
Split into simpler sentences: It roosts on dead, leafless trees, and will also roost on man-made structures such as water or microwave towers. Though it nests in caves, it does not enter them except during the breeding season.