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Some seabirds, principally those that nest in tundra, as skuas and phalaropes do, will migrate over land as well. [ 4 ] [ 72 ] The more marine species, such as petrels, auks and gannets , are more restricted in their habits, but are occasionally seen inland as vagrants.
In most seabird colonies several different species will nest on the same colony, often exhibiting some niche separation. Seabirds can nest in trees (if any are available), on the ground (with or without nests), on cliffs, in burrows under the ground and in rocky crevices. Colony size is a major aspect of the social environment of colonial birds.
Furthermore, it has been proposed that birds that nest in high densities, as seabirds do in breeding colonies, have higher rates of EPCs and EPFs than birds that do not nest colonially. [46] Despite this, Westneat and Sherman (1997) [49] found no significant correlation between nesting density and EPFs in a meta-analysis. Many seabird species ...
A few species nest in small or dispersed groups, but most breed in colonies of up to a few hundred pairs, often alongside other seabirds such as gulls or skimmers. [5] Large tern species tend to form larger colonies, [ 18 ] which in the case of the sooty tern can contain up to two million pairs.
The eggs and chicks of other seabirds, primarily penguins, are an important food source for most skua species during the nesting season. [ 6 ] In the southern oceans and Antarctica region, some skua species (especially the south polar skua ) will readily scavenge carcasses at breeding colonies of both penguins and pinnipeds .
Where it nests on the tundra in the far north, the Arctic skua (Stercorarius parasiticus) is a terrestrial predator, but at lower latitudes, it is a specialised kleptoparasite, concentrating on auks and other seabirds. It harasses puffins while they are airborne, forcing them to drop their catch, which it then snatches up.
Unusual nest sites include hay bales, a stump 0.6 m (2 ft) above the water, and floating logs or vegetation. There is a record of a common tern taking over a spotted sandpiper nest and laying its eggs with those of the wader. [60] Outside the breeding season, all that is needed in terms of habitat is access to fishing areas, and somewhere to land.
Seabirds fly low over water but gain altitude when crossing land, and the reverse pattern is seen in land birds. [34] [35] However most bird migration is in the range of 150 to 600 m (490–2,000 ft). Bird strike Aviation records from the United States show most collisions occur below 600 m (2,000 ft) and almost none above 1,800 m (5,900 ft).