Authorities in northern Illinois are alerting residents that they could encounter an increasing number of coyotes during the mating season over the next few months.
They say pet owners should be particularly aware because the animals are opportunistic and can go after easy prey.
An alert from the city of Wheaton said pet owners should keep their animals on a leash as a precaution. It also suggested people use what experts call "hazing techniques" such as loud noises and threatening gestures.
The Chicago Sun-Times reports that the Naperville police issued a similar advisory, adding that cats and dogs should not be left unattended in yards.
The warnings follow a number of recent coyote attacks on dogs in the Chicago area.