Invasive alien species (IASs) on islands have broad impacts across biodiversity, agriculture, economy, health and culture, which tend to be stronger than on continents. Across small-island developing states (SIDSs), although only a small number of IASs are widely distributed, many more, including those with greatest impact, are found on only a small number of islands. Patterns of island invasion are not consistent across SIDS geographic regions, with differences attributable to correlated patterns in island biogeography and human development.

Seabirds drastically transform the environmental conditions of the sites where they establish their breeding colonies via soil, sediment, and water eutrophication (hereafter termed ornitheutrophication).

Invasive plants and animals inflict much damage on native species and this is particularly the case on isolated oceanic islands with high degrees of endemism. Such islands commonly are important refugia for species of high conservation value. Some of the most pervasive and potent of invasive animal species are birds of the myna (Acridotheres) and bulbul (Pycnonotus) genera that historically were introduced to isolated islands as biological control agents for the management of insect pest species that can cause considerable economic damage to agricultural crops and wider ecosystems.

More than US$21 billion is spent annually on biodiversity conservation. Despite their importance for preventing or slowing extinctions and preserving biodiversity, conservation interventions are rarely assessed systematically for their global impact. Islands house a disproportionately higher amount of biodiversity compared with mainlands, much of which is highly threatened with extinction. Indeed, island species make up nearly two-thirds of recent extinctions. Islands therefore are critical targets of conservation.

Many neglected tropical zoonotic pathogens are maintained by introduced mammals, and on islands the most common introduced species are rodents, cats, and dogs. Management of introduced mammals, including control or eradication of feral populations, which is frequently done for ecological restoration, could also reduce or eliminate the pathogens these animals carry. Understanding the burden of these zoonotic diseases is crucial for quantifying the potential public health benefits of introduced mammal management.

Attempts to eradicate invasive terrestrial arthropods are often regarded as gambles. They o?er the possibility of long term freedom from a pest but are usually confronted with substantial uncertainty and come with a range of technical, economic, environmental, social and political risks. Few guidelines are available for evaluating eradication attempts against terrestrial arthropods.