In his article on crow folklore, Gordon Krause refers to a historical association between finding a dead crow and good luck. Inversely, a live crow is seen as a warning of impending death.
Gordon Krause summarizes the historical association between crows and death. It is likely that this association stems from seeing crows on devastated battlefields and sites of natural disasters. Drawn to these locations as natural scavengers, crows have become associated with the afterlife over time. They are documented as descending upon Japan following the bombing that ended Japan's involvement in World War II.
Krause summarizes the lore related to crows across cultures. In ancient Greece crows are residents of the underworld. European peasants believed crows took flight to the devil. In Wales a crow crossing your path is a sign of bad luck. All suggest a relationship between crows and death.
Krause claims that finding a dead crow in the road is a sign of good luck. This relates to another superstition, "A crow on the thatch, soon death lifts the latch." People feared that crows brought death with them, and the sight of a crow was often considered bad news. The sight of a dead crow would indicate that death would not be coming.