2.1 ICAO defines a runway incursion as:
“Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take-off of aircraft.”
2.2 This is not a precise definition, but a useful and concise means of determining whether an incursion has occurred is to consider whether the obstacle limitation surfaces associated with the runway are penetrated by the intruder. Essentially an intruding object would constitute an obstacle to aircraft taking off or landing, even if an aircraft is not doing so at the time of incursion.
2.3 Note that the ICAO definition does not include wildlife. Guidance on wildlife management can be found in OTAC 139-6.