Approximately 200 dead crows were recently found near Northam on the Great Eastern Highway in Western Australia and there was concern that they may have died from Avian Flu. A bird pathologist examined the remains of all the crows and confirmed the problem was definitely NOT Avian Flu (to everyone's relief). However, he determined that 98% of the crows had been killed by impact with trucks and only 2% were killed by an impact with a car.
The State Government then hired an ornithological behaviourist to determine the disproportionate percentages for truck versus car kills. The ornithological behaviourist determined the cause. The conclusion in short order was: When crows eat road kill, they always set-up a look-out crow in nearby trees to warn of impending danger.
His conclusion was that the lookout crow could say "Cah", but he could not say "Truck."