I just read article that said that crows were being killed at high number on the highways. Further research showed that they were being killed by trucks. Seems though, according to the study,that when a group of crows fine a road kill they will gather at the site and post a sentinel to warn of any approaching vehicles. What they also determined was that the sentinels can say "Caw...Caw...Caw..but can't say "Truk...Truk...Truk" Just reporting the facts folks.