A recent Alberta Government study, has found over 200 dead crows near Calgary, Alberta and there was concern that they may have died from the Avian Flu virus. A Bird Pathologist examined the remains of all the crows, and he confirmed the problem was definitely NOT Avian Flu, to everyone's relief.
However, he was also able to determine that 98% of the crows had been killed by impact with large trucks, and only 2% were killed by car impact.
The Provincial Government hired an Ornithological Behaviorist from Toronto to determine the disproportionate percentages for the large truck versus car kills .The Ornithological Behaviorist determined the cause in short order. When crows eat road kill, they always set-up a look-out crow in a nearby tree to warn of impending danger.
His conclusion was that the lookout crow could say "Cah", but he could not say "Truck."
(Yeah, yeah, yeah, ... you got a better one?)