Rookery - Nesting Colonies

How Colonial Birds Nest


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Named for the communally-nesting rook (Corvus frugilegus) of Europe and Asia, rookeries are large, clustered nesting colonies. In the rookery, each nest is typically independent, with parent birds caring for only their nestlings and generally disregarding the behavior of other nearby nests, adults, or chicks. In some cases, parent birds may be aggressive toward other adults or young birds that invade the personal space of their nest, though that personal space margin varies widely for different bird species.

What Is a Rookery?

A rookery is a communal nesting ground for gregarious birds. While birds do not share individual nest duties, the collection of nests in a small area gives nesting birds and vulnerable chicks extra protection and advantages.

Though individual nests are independent, there are benefits for birds to nest in colonial groups. With more adult birds in the area, predators may be spotted more quickly and pose less of a threat to the group as a whole. Multiple adult birds may also gang up on intruders to defend the nesting area if necessary.

Most rookeries are found in wetland areas or locations where many suitable nesting sites may be scarce. Large trees or groups of trees are favored rookery locations and islands are especially popular for nesting wading birds, because the surrounding water provides a natural protective barrier for the nests. Birds can also become accustomed to artificial rookeries, which are usually large towers with multiple nesting platforms to accommodate many bird families.

In general, while the term rookery can be used for any group of colonially nesting birds, it is reserved for nesting areas that occur in trees or on elevated artificial platforms resembling tree-like structures. Colonial nesting areas on the ground, such as with albatrosses, flamingos, and penguins, are not generally considered rookeries.

About Rookeries

Birds That Nest in Rookeries

A number of bird species commonly nest in rookeries. The birds that do well in these group nesting situations are generally sociable and are often found in flocks throughout the year, including when feeding, foraging, or roosting. Most rookeries are composed of primarily one bird species, though when different nesting birds have similar habitat and nesting requirements, the rookery may be made up of nests from different species.

Types of birds that are most familiar in rookeries include:

  • Anhingas
  • Cormorants
  • Darters
  • Egrets
  • Herons
  • Ibises
  • Night-herons

Several types of corvids, including oropendulas, rooks, and different crows, also nest in rookeries.

In addition to birds, the nesting colonies of seals, sea lions, and some turtle species can also be called rookeries.

Problems With Rookeries

Rookeries may have several benefits for birds, but they can cause problems for humans. When a large rookery is near a neighborhood, the noise and mess from feces and molting down from hundreds of young birds can be problematic and controversial. Similarly, many piscivorous birds feeding in a small area near an active rookery can be upsetting for local commercial fishing operations or tourist fishing organizations. Birds that nest in rookeries will return to the same nesting site for many years, so the size of the rookery will grow and any problems may also get larger year after year.

Because nesting birds are protected under different laws and legislation such as the Federal Migratory Bird Treaty Act, it is illegal to disturb the nests or harm the eggs, chicks, or adult birds. In cases where a rookery is causing an extreme problem, local wildlife officials may be consulted to evaluate the situation and suggest appropriate action to encourage the birds to nest elsewhere. If the rookery is new and resources are available, officials may even attempt to relocate nests. These actions should not be taken by unauthorized individuals, however, and anyone interfering with a rookery can face severe penalties including fines, jail time, and other repercussions.

Visiting a Rookery

A rookery can be an excellent opportunity for birders to observe nests, nesting behavior, and young birds, and they are also popular subjects for bird photography. It is vital to avoid disturbing the birds in any way, however, and visitors should be extremely cautious to keep from disrupting nests. To safeguard the rookery and its residents:

  • Stay a respectful distance from active nests, using spotting scopes and telephoto lenses to get closer rather than approaching the area directly. Many monitored rookery areas will be off-limits to visitors during the peak of nesting season, or barriers may be erected to keep visitors a suitable distance away.
  • Protect the habitat surrounding the rookery. Adult birds will forage frequently to find enough food to provide for hungry nestlings, and the best nearby feeding areas can be depleted quickly. If the adjacent habitat is contaminated or unsuitable, the entire rookery could be at risk of starvation, and adult birds may begin to abandon nests.
  • Report any suspicious or unlawful behavior to the proper authorities, including illegal hunting and poaching, trespassing, or any interference with nests, eggs, or birds. Taking photographs of illegal activities or noting distinguishing characteristics like license plates or vehicle details can be useful evidence to pass on to officials.

Also Known As

Breeding Colony, Nesting Colony