Blue Jays glean insects and take nuts and seeds in trees, shrubs, and on the ground;It will also eat pet food left outside and has even been observed predating smaller birds stunned or killed by window strikes Sometimes Blue Jays will imitate hawk calls to startle other birds into dropping or abandoning food, which the jay then grabs Blue jays have good reason to be protective Only a little more than half of their nests produce at least one chick, thanks to the gray squirrels , crows and snakes that often prey on eggs and chicks
Blue Jay Overview All About Birds Cornell Lab Of Ornithology