U.S. Fish & Wildlife ServiceReason for Selection Islands provide important habitat for many species of birds, reptiles, amphibians, mammals, insects, and plants. Due to their isolation, islands tend to be ecologically unique, making them hotspots for species diversity. In addition, the relative isolation of islands from disturbance and mainland predators can make them important breeding habitat for coastal birds and sea turtles. However, these factors also increase islands' vulnerability to invasive species (IUCN 2018). According to Bernie 2015, "islands warrant a unique level of attention for biodiversity conservation because they make up only a small percentage of land area but are known for their many endemic species." This rich diversity is also disproportionately threatened, with "61% of all extinct species and 37% of all critically endangered species confined to islands" (Bernie 2015). The critical habitat included in this indicator refers to areas with specific physical or biological features that are essential to conserving a federally threatened or endangered species and may require special management or protection. Input Data Southeast Blueprint 2023 subregions : Caribbean Caribbean island extent and size Southeast Blueprint 2023 extent Critical habitat provided by the U.S. Fish and Wildlife Survey, accessed 6-23-2022; download the data Threatened Island Biodiversity (TIB) Database, accessed 11-29-2022 This database includes terrestrial vertebrate species that breed on islands and appear on the IUCN Red List as either Critically Endangered or Endangered. It also includes seabird species listed as Vulnerable and terrestrial vertebrates listed as Extinct in the Wild. Puerto Rico Gap Analysis Project (GAP) predicted vertebrate species distributions: data provided by Dr. Bill Gould with the Caribbean Climate Hub on 4-4-2022 (contact william.a.gould@usda.gov for more information); read the final report U.S. Virgin Islands GAP predicted vertebrate species distributions: data and report appendices provided by Dr. Bill Gould with the Caribbean Climate Hub on 2-6-2023 (contact william.a.gould@usda.gov for more information); read the final report Mapping Steps From the TIB Database, in the "Invasive Species on Island" sheet, select islands where "Region_Archipelago" is "Greater Antilles (Puerto Rican Islands)", "US Virgin Islands", "US Virgin Islands (St. Croix Islands)", or "US Virgin Islands (St. Thomas Islands)". Count the number of invasives species records per island, ignoring any row where "Common_Name" is "NONE". From the TIB Database, in the "Threatened Species on Island" sheet, select islands where "Region_Archipelago" is "Greater Antilles (Puerto Rican Islands)", "US Virgin Islands", "US Virgin Islands (St. Croix Islands)", or "US Virgin Islands (St. Thomas Islands)". Count the number of threated species records per island where "Present_Breeding_Status" is "Confirmed" or "Potential Breeding". Combine the invasive and threatened species data using "Island_GID_Code" and fill in invasive or threatened species counts with 0 if islands didn't have a record in either of the sheets. Include only islands < 50 km 2 (smaller than St. Thomas) using the "Corrected_Area_KM2" field. The input data on imperiled species and invasive animals did not include species distributions within individual islands. That was less of an issue on smaller islands but made the source data less informative for larger islands. Extract "Corrected_Latitude" and "Corrected_Longitude" of islands from the "Invasive Species on Islands" sheet, then create shapefile of the summarized data. Spatially join the summarized data from TIB Database to the Caribbean island extent layer. Many species in the island biodiversity database have habitat on large islands, but the database doesn't provide sufficiently detailed species distribution information within those islands to be used as an indicator. To address this, use predicted habitat models from Puerto Rico and U.S. Virgin Islands GAP for species listed in the TIB Database that live on large islands (i.e., >50 km 2) . These species were: Puerto Rican parrot, Culebra Island giant anole, Puerto Rican nightjar, Mottled coqui, Cricket coqui, Hedrick's coqui, Golden coqui, Locust coqui, Forest coqui, Richmond's coqui, Wrinkled coqui, Virgin Island tree boa, and Desecheo dwarf gecko. To prepare the GAP data, begin by fixing issues in two species layers. For Puerto Rican nightjar (Caprimulgus noctitherus), convert NoData to 0 to fill in a square of NoData in the center of Puerto Rico. For forest coqui (Eleutherodactylus portoricensis), add 1 to the values to make them consistent with the values used in the other layers for presence and absence. Sum the values of the species models and subtract by the total number of species to get species counts for each pixel. GAP uses 2 to indicate presence and 1 to indicate absence. Combine the Puerto Rico and U.S. Virgin Islands GAP species counts into a single raster. Then snap and reproject based on the Caribbean Blueprint subregion. Clip the critical habitat to the Caribbean islands extent layer and convert to raster. Include all critical habitat in the area except for yellow-shoulder blackbird. The large area of poor-quality habitat covered by critical habitat for this species was causing significant overprioritization in this indicator and local reviewers recommended removing it. This still results in important areas for the species being included based on models for other species, but greatly reduces overall overprioritization in many places. Combine data from the TIB database, critical habitat, and Puerto Rico and U.S. Virgin Islands GAP as shown in the final indicator values below. Clip to the Caribbean Blueprint 2023 subregion. As a final step, clip to the spatial extent of Southeast Blueprint 2023. Note: For more details on the mapping steps, code used to create this layer is available in the Southeast Blueprint 2024 Data Download or Caribbean-only Southeast Blueprint 2024 Data Download under > 6_Code. Final indicator values Indicator values are assigned as follows: 7 = Island area with critical habitat for a threatened or endangered species 6 = Island area with no invasive animals and 2+ imperiled species 5 = Island area with no invasive animals and 1 imperiled species 4 = Island area with no invasive animals 3 = Island area with invasive animals and 2+ imperiled species 2 = Island area with invasive animals and 1 imperiled species 1 = Island area with invasive animals 0 = Not an island Known Issues This indicator underestimates habitat values for some small islands due to a lack of data in the Threatened Island Biodiversity Database. For some areas on large islands, like Vieques National Wildlife Refuge, it underestimates habitat values due to a lack of detailed distribution models for some species. This indicator likely underpredicts important habitat for federally listed species. Not all federally listed species have critical habitat designated, and not all of the critical habitat data designated by the U.S. Fish and Wildlife Service is available from the data source used. Disclaimer: Comparing with Older Indicator Versions There are numerous problems with using Southeast Blueprint indicators for change analysis. Please consult Blueprint staff if you would like to do this (email hilary_morris@fws.gov ). Literature Cited Bernie R. Tershy, Kuo-Wei Shen, Kelly M. Newton, Nick D. Holmes, Donald A. Croll, The Importance of Islands for the Protection of Biological and Linguistic Diversity, BioScience, Volume 65, Issue 6, June 2015, Pages 592-597. [ https://doi.org/10.1093/biosci/biv031 ]. Gould, William A.; Alarcón, Caryl; Fevold, Brick; Jiménez, Michael E.; Martinuzzi, Sebastián; Potts, Gary; Quiñones, Maya; Solórzano, Mariano; Ventosa, Eduardo. 2008. The Puerto Rico Gap Analysis Project. Volume 1: Land cover, vertebrate species distributions, and land stewardship. Gen. Tech. Rep. IITF-GTR-39. Río Piedras, PR: U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry. 165 p. [ https://data.fs.usda.gov/research/pubs/iitf/iitf_gtr39.pdf ]. Gould WA, Solórzano MC, Potts GS, Quiñones M, Castro-Prieto J, Yntema LD. 2013. U.S. Virgin Islands Gap Analysis Project - Final Report. USGS, Moscow ID and the USDA FS International Institute of Tropical Forestry, Río Piedras, PR. 163 pages and 5 appendices. [ https://usfs-public.app.box.com/s/rtywvcylj7g0ppqabgl7nb4qmw28209j ] IUCN (2018). Guidelines for invasive species planning and management on islands. Cambridge, UK and Gland, Switzerland: IUCN. viii + 40pp. [ https://portals.iucn.org/library/sites/library/files/documents/2018-030-En.pdf ]. Sayre, R., S. Noble, S. Hamann, R. Smith, D. Wright, S. Breyer, K. Butler, K. Van Graafeiland, C. Frye, D. Karagulle, D. Hopkins, D. Stephens, K. Kelly, Z, basher, D. Burton, J. Cress, K. Atkins, D. van Sistine, B. Friesen, B. Allee, T. Allen, P. Aniello, I Asaad, M. Costello, K. Goodin, P. Harris, M. Kavanaugh, H. Lillis, E. Manca, F. Muller-Karger, B. Nyberg, R. Parsons, J. Saarinen, J. Steiner, and A. Reed. 2018. A new 30 meter resolution global shoreline vector and associated global islands database for the development of standardized global ecological coastal units. Journal of Operational Oceanography-A Special Blue Planet Edition. [ https://doi.org/10.1080/1755876X.2018.1529714 ]. Threatened Island Biodiversity Database Partners. 2018. The Threatened Island Biodiversity Database: developed by Island Conservation, University of California Santa Cruz Coastal Conservation Action Lab, BirdLife International and IUCN Invasive Species Specialist Group. Version 2018. Downloaded on November 2022. [ https://tib.islandconservation.org/ ]. U.S. Fish and Wildlife Service. Critical Habitat. Accessed June 23, 2022. [ https://ecos.fws.gov/ecp/report/table/critical-habitat.html ].ArcGIS ImageMapLayerhttps://hub.arcgis.com/datasets/dca9fcb28ec34a6e98aa43227e21b871engU.S. Fish and Wildlife Service Open DataPublicCaribbean Island Habitat (Southeast Blueprint Indicator) [United States]Web servicesUnited StatesLast Modified: 2025-08-25