Bird colony

Colonial nesting birds include seabirds such as auks and albatrosses; wetland species such as herons; and a few passerines such as weaverbirds, certain blackbirds, and some swallows.

Evidence of colonial nesting has been found in non-neornithine birds (Enantiornithes), in sediments from the Late Cretaceous (Maastrichtian) of Romania.

[4] Colony-nesting birds often show synchrony in their breeding, meaning that chicks all hatch at once, with the implication that any predator coming along at that time would find more prey items than it could possibly eat.

Tufted puffins, for example, are pelagic birds that nest on the steep slopes and rocky crevices on coastal cliffs, often on islands.

Triangle Island, for example, the largest seabird colony in British Columbia, Canada, is home to auks, gulls, cormorants, shorebirds, and other birds, as well as some marine mammals.

This increases breeding success, provides a place for returning mates to reunite, and reduces the costs of prospecting for a new site.

The white-winged dove of southwestern North America was known to nest in large colonies when foraging areas could support such numbers.

In 1978, in Tamaulipas, Mexico, researchers counted 22 breeding colonies of white-winged doves with a collective population size of more than eight million birds.

Another suggestion is that colonies act as information centers and birds that have not found good foraging sites are able to follow others, who have fared better, to find food.

Although scientists have hypothesized about the advantages of group nesting in terms of enabling group defensive behavior, escape from predation by being surrounded by neighbors (called the selfish herd hypothesis), as well as escaping predators through sheer numbers, in reality, each of these functions evidently depends on a number of factors.

One well-studied case of this phenomenon has been the effect on common murre colonies on islands in Alaska, where foxes were introduced for fur farming.

[22] Colony-nesting birds have been used by humans as a source of food in the form of eggs and meat, down for bedding, feathers for quill pens, and guano for fertilizer.

Likewise, the short-tailed albatross of the North Pacific was heavily harvested at what seems to have been its primary colony on Torishima Island.

Case in point: in 1871, in Wisconsin, an estimated 136 million pigeons nested in a dense congregation over a wide area; thousands of people were drawn to hunt the birds, shipping the squab to market by rail.

[23] The use of seabird droppings as fertilizer, or guano, began with the Indigenous Peruvians, who collected it from sites along the coast of South America, such as the Chincha Islands.

When, after the Spanish Conquest, the value of this fertilizer became known to the wider world, collection increased to the point where the supply nearly ran out, and other sources of guano had to be found.