Interesting situation near Boston. They found about 200 crows dead, and though it might be some kind of avian virus. A pathologist examined the remains of all the crows, and confirmed the problem was definitely not a virus
Instead, the cause of death was vehicular impacts. It was noted that different types of of paints appeared on the bird's beaks and claws. By analyzing the residue, it was determined that 98% of the crows had been killed by impact with trucks, while only 2% were killed by an impact with a car.
The matter was studied further by ornithologists to determine the cause for the disproportionate percentage of truck kills versus car kills. They quickly found the cause. When crows eat road kill, they always have a look-out crow in a nearby tree to warn of impending danger. While all the lookout crows could shout "Cah", not a single one could shout "Truck."
Ba-dum-dum.