They do not need to be dirt strips for wild life the RFDS WA section lost 4 Garret TPE 331 engines in around a week on 3 aircraft. 2 were wildlife on 2 separate sealed strips. The other was a dirt strip at Cotton Creek in the Little Sandy Desert, the pilot was off the runway turning around (after rain) when the nose started to get bogged. Application of "much" more power gave the sensation of forward movement until the nose leg collapsed. This as you would be aware created a double propeller strike even ripping one gear box apart - now if this was say the jet, how many engines would need to be changed?
The same for the other 2 aircraft that hit wildlife, it is the propeller that caused the costly repairs.