What is the source of the pressure that has caused coyotes, which were once essentially diurnal, to adjust to a more nocturnal behavior?

The source of the pressure that has caused coyotes, which were once essentially diurnal, to adjust to a more nocturnal behavior is the presence of more aggressive diurnal predators, more commonly, lions. Lions only hunt in the day which limits the activity of the coyotes. As a result, the coyotes change their hunting schedules to nighttime to reduce competition.