The blue jay is a slow flier ( 32–40 km/h (20-25 mi/h) when unprovoked) and an easy prey for hawks and owls, when it flies in open lands. It flies with its body and tail held level, with slow wing beats. It is sometimes assertive toward other birds and may chase birds from bird feeders or other food sources, although this happens much less often than it is blamed for. This can be good to other species as well, as it may chase predatory birds, such as hawks and owls which sometimes feed on jays, and will scream if it sees a predator within its territory. It has also been known to sound an "alarm call" when hawks or other dangers are near, and smaller birds often know this call and hide themselves away accordingly. It may also be aggressive towards humans who come close to its nest, and if an owl roosts near the nest during the daytime the blue jay mobs it until it takes a new roost.