Islands exhibit the planet’s most unique flora and fauna, but the diversity on islands is
also vulnerable to impending forces of global change. Scattered across the Pacific Ocean
>20,000 islands range from sandspits to large islands and support some of the most
unique biotic assemblages. Shaped by island size, topography and degree of isolation
from other landmasses, including continents and other islands, insular systems support
the largest number of endemic flora and avifauna. Because of the mobility associated
with flight, birds have colonized the most remote islands, and are one of the most
important taxa in insular systems.
The unique characteristics of islands provide habitat and resources for of avian
species, including resident, migrants and seabirds. For many species, islands and
archipelagos extremely important, they represent full habitat ranges, and for others may
provide key resources, including migration stopover sites and suitable habitat for
reproduction and nesting. Insular organisms are often naïve to foreign forces, and island
species are susceptible to introduced competitors and predators from continental origins
and the effect of anthropogenic processes. Almost without exception, island habitats and
species have been impacted by invasive species and anthropogenic processes – islands
systems exhibit the highest rate of avian extinctions. Habitat alteration and introduced
species often have detrimental effects in insular biota. The effects range from native
habitat disturbance to the annihilation of native species, including endemics (e.g., Tern
island and Guam).