Ravens form large, loosely packed groups of birds. They are known to fly and roost together, though they don’t have many strong social bonds like the ones typically seen in flocks of geese.
Birds will sometimes motor from large daytime feeding areas to nighttime resting sites in ‘raven flights’. When there is migration or nomadic movement at night, such as with shorebirds or red-winged blackbirds that don’t perch during the day, these groups of migrating birds (such as corvids) leave their safe nesting site and may be vulnerable to robbers, such as other carnivorous birds; hence when ravens flock together at night this way it can make them safer. It may also enable communication and safety in numbers.
Ravens will also assemble alongside other species, such as magpies and dogs (this is why ravens and dogs don’t typically get along well).
There are reports of ravens nesting in massive aggregations, or ‘raven cities’ where thousands have been seen together. Ravens have been observed to nest in large groups when there is a high population of food sources, such as salmon runs.
