Blue Jay

Flock of singing Blue Jays, Cyanocitta cristata

The Blue Jay is a common sight and sound along the eastern half of the United States and parts of southern Canada year round. This bird is readily associated with its harsh, loud jeer call, but also contains a less heard whisper song that can last for minutes. Blue jays are birds that often form loose flocks, especially as the colder weather arrives, much like the American Robin. Most do not migrate, but there are records of migrating blue jays usually near shorelines which is where flocking is most likely to occur. While resident blue jays also flock, it is much more loose and less predicable.

Another cause for flocking occurs through a behavior known as mobbing. It is not exclusive to blue jays, but can be seen in other songbirds including the American robin, chickadees, crows, the tufted titmouse, and cardinals. A loud congregation of these species is often an indication that a raptor is being mobbed by a flock of songbirds. The victim is often a residential raptor such as the suburban adapted Eastern Screech-Owl. Although mobbing is a risky behavior, there are hypothesis that this could be related to nest-defense, a way of warning young of potential dangers, or possibly even a source of fun for certain species.

This video contains what I think is the described song of the blue jay. If I had not seen them, I wouldn't have guess it was actually blue jays. This is not a mobbing congregation, but likely the local residents flocking together as the weather changes.