A mixed flock occurs when members of different species feed or live together. This behavior usually is more prevalent outside the breeding season. For example, Leonard and I often see warblers, chickadees, nuthatches, kinglets and/or woodpeckers feeding or moving together in the winter.
Birds may form mixed flocks for several reasons:
*There is safety in numbers. More “eyes” can detect danger more quickly and many birds flying in different directions can confuse predators.
*More birds can overwhelm territorial defenses. A large group may be able to feed where a single bird might be ejected by the “owner” of a territory.
*More individuals searching for food means food is more likely to be found.
*Birds in a group can learn about new food sources from other species.
*The birds may simply enjoy each others’ company.
While walking along the auto trail in Ash Creek Wildlife Area (Lassen County CA), we saw a large “mixed flock” of greater white-fronted geese (Anser albifrons) and sandhill cranes (Antigone canadensis). Greater white-fronted geese and sandhill cranes interacting and feeding together probably do not fit the definition of a true mixed flock. However, it was interesting to watch these two species engage.