The Northern Saw-whet Owl - Aegolius acadicus - hunt mainly at dusk and dawn and most often use the "sit and wait" tactic to drop down onto prey on the ground from low hunting perches. All text from www.owlpages.com
They will also range through wooded areas and hunt in heavy shrub cover. When prey is plentiful, a Saw-whet Owl will kill as many as 6 mice in rapid succession, without consuming any of them.
Northern Saw-whet Owls feed almost entirely on small mammals, Deer mice being the primary prey, followed by shrews and voles. Other mammals include squirrels, moles, bats, flying squirrels, and house mice.
Small birds are sometimes taken and include swallows, sparrows, chickadees, and kinglets. Larger birds such as Northern Cardinal and Rock Dove can be killed by one of these small Owls. Frogs and insects are also part of their diet.
The excess food is cached in safe places and, in winter, is thawed out later by "brooding" the frozen carcass. When food is plentiful, it is common for only the head of each prey to be eaten. This owl was photographed near the corner of 18th Street and Michigan Avenue, Chicago