Gregarious - Bird Flocks

Types of Bird Flocks and Flocking Behavior

Flock of American Coots
Many waterfowl, such as American coots, are highly gregarious. Photo © Tom Koerner/USFWS/Flickr/CC by 2.0

Definition:

(adjective) Gregarious describes a bird species that is sociable and forms large flocks. Many bird species form flocks for foraging, roosting or breeding, including communal flocks at nesting colonies where all chicks may be raised together. Migration is another time when large flocks form in bird species that may otherwise be more solitary.

Pronunciation:

grih-GAIR-eee-us
(rhymes with hilarious, precarious and aquarius)

About Gregarious Behavior

The term gregarious is generally only used to denote large bird flocks, not just a few birds gathered together. The size of the flock can vary from a few dozen birds to thousands of individuals, and some highly gregarious birds may even gather in flocks of a million or more individual birds. Personal space within the flock also varies, with some birds grouped tightly together while others are spaced out more widely.

Some species form these large, gregarious flocks throughout the year, while others only form large flocks in certain seasons. The most frequent time for large flocks to form is in late summer after the breeding season ends and birds are coming together to prepare for migration, often in areas where food and other resources are most abundant. Bird species that do not migrate may also be gregarious, however, as they gather at prime feeding areas to collect food to cache for the winter.

When birds are considered gregarious, it is often assumed that they associate only in large flocks of their own kind. While this is often true, the composition of the flock can also vary and may include several bird species with similar needs, such as mixed flocks of waterfowl or sparrows.

Benefits and Problems of Being Gregarious

Gregarious behavior is beneficial to birds because it provides protection in numbers and gives each individual a better opportunity for survival.

A roosting flock, for example, will generate body warmth in cold weather that can help the group stay more comfortable. Similarly, a foraging flock will have more success finding food or watching for predators than an individual bird. During migration, a large flock of birds has many more eyes to watch for landmarks and resources along the way, and fewer birds are likely to get disoriented or lost.

On the other hand, a large, active flock of birds can also have significant problems. Hungry predators will be able to more effectively hear, smell and see a large flock of birds, and some members of the flock are certain to become prey. Wild bird diseases are also more devastating to large flocks, where bacteria and viruses can be efficiently transmitted to many birds at once. If food supplies are scarce, a large flock will more quickly use up available food and not all the birds may be able to find enough to eat.

What Being Gregarious Isn't

It is important to note that not all bird flocks are necessarily gregarious. There are many times when birds will group together but they are not being social enough to be considered gregarious, such as...

  • Family Groups: Many bird species will stay together as family groups as young birds mature, and in fall and winter those groups could seem like larger flocks if several large broods were raised. In some birds, older juvenile birds may even assist with raising younger siblings from later broods, making the flock seem even larger, but that does not mean the birds are truly gregarious.
     
  • Backyard Feeding Stations: Backyard birders often provide a variety of different foods, feeder styles and water at a feeding station. This may attract a wide range of bird species, but the birds would not naturally congregate so closely and are not considered gregarious when they gather at an artificial feeding area.
     
  • Aviaries and Other Captive Birds: Birds in captivity - zoos, aviaries, rehabilitation facilities, farms, pet stores, etc. - live and behave in different ways than their natural instincts. These birds may seem gregarious, but artificial environments do not always reflect the bird's true nature.

Watching Gregarious Birds

All birders have seen flocks of different sizes, but watching truly gregarious birds can provide intriguing insights into bird behavior. When observing a large flock, birders can see just how maneuverable birds can be in their aerial acrobatics, including how well they maintain flight differences in the air.

Different bird personalities can also be better observed when birds are interacting in a group, and birders may also see unique flock behaviors such as...

  • Synchronized mating dances or other group displays
  • Unusual noises as the calls and sounds of hundreds of birds blend together
  • Communal activities, such as cooperative feeding or mobbing predators

It is important not to startle a large, gregarious flock, however. When one bird initiates an alarm, many, many birds are likely to react and the disruption to the birds' activities can be extreme. Birders should keep their distance from large flocks, and instead use the opportunity for fascinating observations.

Familiar Gregarious Bird Species

Many birds will be part of flocks of various sizes, but not all flocking birds are equally gregarious. The most familiar bird species well known as easily gregarious include European starlings, red-winged blackbirds, budgerigars, red-billed queleas, emperor penguins and many types of ducks, geese and other waterfowl.

See Also: Names of Groups of Birds

Also Known As:

Social, Sociable