A new inventory and conservation assessment of United States islands

Annals of the American Association of Geographers
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Abstract

To support conservation-focused research and management we developed a new 30-m resolution polygon data layer of the nonlacustrine and nonriverine islands of the United States, with associated attributes describing key physical and conservation geography characteristics. Islands were grouped into a three-tiered hierarchy of island regions (twelve), island provinces (twenty-eight), and individual islands (19,023). Islands were classified as either continental or oceanic based on their physiographic position relative to the North America continental shelf, and estuarine versus nonestuarine depending on their location within or external to estuaries. For each island we assessed the diversity of terrestrial and coastal ecosystems, the number of threatened and endangered (T&E) species listed under the Endangered Species Act, the number of T&E species critical habitats, the number of migratory bird species listed under the Migratory Bird Treaty Act, the number of Key Biodiversity Areas, and the number of and management responsibility for protected areas. We conclude that the conservation importance of islands is disproportionate to their total area as, for example, islands contain 52 percent of the T&E species yet their total area is only 2 percent of the area of the continental mainland. Similarly, of the global total of 431 World Terrestrial Ecosystems, 201 (47 percent) occur on U.S. islands compared with 286 (66 percent) that occur on the U.S. continental mainland.

Suggested Citation

Sayre, R., Martin, M.T., Naji, N., Sides, K.B., Cress, J., Butler, K., Van Graafeiland, K., Karagulle, D., Frye, C., Breyer, S., Wright, D., Klavitter, J., Spatz, D., Will, D., Howald, G., Wegmann, A., Stanley, C., Holmes, N., 2026, A new inventory and conservation assessment of United States islands: Annals of the American Association of Geographers, https://doi.org/10.1080/24694452.2025.2604843.

Publication type Article
Publication Subtype Journal Article
Title A new inventory and conservation assessment of United States islands
Series title Annals of the American Association of Geographers
DOI 10.1080/24694452.2025.2604843
Edition Online First
Publication Date January 14, 2026
Year Published 2026
Language English
Publisher Taylor and Francis
Contributing office(s) Geosciences and Environmental Change Science Center, Land Change Science
Country United States
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