Researchers for the Maine Turnpike Authority recently found over 200 dead crows along the turnpike, and moreso the further north they went, and there was concern that they may have died from Avian flu. They had a Bird Pathologist examine the remains of all the crows.
To everyone's relief, he confirmed the problem was definitely not Avian flu.
However, he determiend that 98% of the crows had been killed by impact with trucks and only 2% were killed by an impact with a car.
Maine then hired an Ornithological Behaviorist to determine the cause of the disproportionate percentage for truck kills verus car kills.
The Ornithological Behaviorist determined the cause in short order. When crows eat road kill, they always have a look-out crow in a nearby tree, to warn of impending danger.
His conclusion was that, while all the lookout crows could say "Cah", none could say "Truck."