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Seabird islands house large colonies of seabirds that spend most of their time at sea but return to land to breed. Seabirds deposit large amounts of nutrients of marine origin on islands; many species also disturb soil and vegetation during the building and maintenance of nests. Physical and chemical disturbance by seabirds alters the chemical composition of soils and vegetation and modifies plant and animal communities. In many cases, the additional nutrients brought in by seabirds subsidise native animal populations, including endemic species frequently found on remote islands. Introduction of predators such as rats, cats and mustelids has resulted in population decreases or local extinction of many seabird species, and this leads to large changes in nutrient cycling and plant and animal populations. Recent efforts at eradication of introduced seabird predators have been successful, but re-establishment of seabirds and seabird island communities will likely take additional active restoration. Key Concepts: Seabirds deposit nutrients of marine origin in terrestrial environments. Seabirds impose physical disturbance on soils and vegetation in the process of building and maintaining nests. Seabird islands often house endemic and native plants and animals that are no longer found on the mainland. The presence of seabirds selects for plants that are tolerant of high-disturbance and high-nutrient conditions. Nutrient subsidies from guano (i.e. nitrogen and phosphorus) can support increased primary and secondary productivity. Introduced mammalian predators have eradicated seabirds and other species on many seabird islands. The reduction of seabird populations by introduced predators alters plant and animal communities and nutrient cycling. Eradication of seabird predators is a necessary first step towards restoration of seabird islands. Restoration of seabird islands often requires active management of seabirds, other animals and plant populations. Protection of seabird islands will require international cooperation on land and at sea. Keywords: allochthonous inputs; ecosystem engineering; invasive predators; island endemism; island restoration; nutrient subsidies; physical disturbance; predator eradication; superpredator |
