The bats are probably just busy eating oranges. Oh man, look at that old comic being old.
Owls have good hearing. Maybe sandmen can talk to the owls with sounds that to us would be ultrasonic.
To do stuff like tell them what their destination is, and to pay their taxi fare.
Yes, Sandman is at least capable of ultrasonic whistling. http://www.ashleyappletree.com/?p=459 which would suggest he can hear it, too. But shh, don’t tell Ashley.