Grumman American Undifferentiated or Other Model
Air Traffic Control Fully Certified
Human-Machine Interface; Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors; ATC Equipment / Nav Facility / Buildings
I was working Local and Ground control combined. I had airport security on Runway 8 looking for birds on or near the runway because an aircraft had reported sightings of birds near the runway to the previous Controller. I later cleared Aircraft X for takeoff off of Runway 8 and right after this airport security reported clear of Runway 8 and standing by. The aircraft had just started to move from his stopped position and had not yet crossed the hold short lines of Runway 8 at this time; so I told Aircraft X cancel takeoff clearance then verified with the vehicle as well as visually scanning that airport security was indeed clear of Runway 8 and proceeded to clear Aircraft X for takeoff again. Maybe a flashing runway incursion light that makes noise.
Tower Controller reported clearing an AA2 for takeoff; having forgotten an airport vehicle was on the runway.  The clearance was canceled before any conflict developed.