International Working Group
Over half of all bird species nesting in the U.S. are classified as neotropical (also called neotropical-nearctic) migratory birds. Some or all of the populations of 338 species—which include many of our songbirds, waterfowl, birds of prey, waterbirds and shorebirds—migrate each fall to the tropics. Billions of neotropical migrants fly southward to Latin America searching for suitable tropical wintering grounds. In addition to being up to eight times more concentrated on wintering grounds than on their breeding areas, these migrants also share their wintering habitats with the resident tropical species. The effect of this concentration makes the loss and alteration of tropical habitats especially destructive to neotropical migratory bird populations. Even the most effective management of habitats on U.S. military lands may appear deficient if migratory bird populations suffer losses in the non-breeding seasons. And recent research suggests that the physical condition of birds when they leave the non-breeding grounds has more influence on breeding productivity than any factor on the breeding grounds.
Habitat destruction and disturbance are the primary threats to West Indian birds. Over the past several centuries, approximately 9 out of 10 avian extinctions have been of endemic island species. Many neotropical migrants share these same habitats and are also adversely affected by their destruction and disturbance. Tropical arid scrub, mud flat, and mangrove and tropical dry forest habitats provide critical stopover and wintering habitat for neotropical migrants and support numerous island endemics. Scientists are studying these habitats, the impacts of weather and climate on migration patterns, and others factors affecting productivity and survivorship of bird species on Navy installations in Puerto Rico and Cuba. In particular, DoD lands offer the greatest potential for preserving and improving habitat conditions in the West Indies. These current and former DoD sites sustain some of the best remaining mangrove habitats in the West Indies.
The Panama Canal Treaty of 1977 stated that lands currently held by the United States were to revert back to Panamanian ownership and control by the year 2000. Recognizing the significance of the canal lands to the biodiversity of Panama, as well as the United States and countries in between, DoD PIF convened several meetings to bring together biologists, economic development leaders, and politicians. The International Working Group of PIF met in Panama City in 1996 to document the economic, ecological, and cultural values associated with the canal lands. The report, The Key Role of Specific Lands in the Panama Canal Area in Preserving the Value of Panama’s Natural Heritage, was distributed to interested partners throughout Panama. A follow-up workshop held in 1998 built on the previous workshop and explored options for obtaining the right balance of conservation and economic sustainability. As a result of these efforts, Panama has a developing ecotourism effort, and over 150,000 acres of former DoD lands are now identified as Important Bird Areas. Many of the best of these lands have been incorporated into Panama’s national park system.
The Upper Bay of Panama hosts some of the largest concentrations of migrant and overwintering shorebirds in the Western Hemisphere. A study funded through DoD PIF documented a high single day count of nearly 300,000 Western Sandpipers in fall migration. The study helped the upper Panama Bay achieve status as both a Western Hemisphere Shorebird Reserve Network site of hemispheric significance and a RAMSAR site (wetland of international significance). A resurvey was conducted in the fall of 2008 to assess changes over the previous decade. Current efforts, funded by the Legacy program, are examining this species’ use of military lands as migration stopover sites linking Panama, Mexico, the U.S. and Canada.
The last active Navy lands in Puerto Rico closed in March 2004. Historically, mangroves covered about 60,000 acres of coastal lowlands of Puerto Rico. Located along the island’s eastern coastline, the former Naval Station Roosevelt Roads contains about 2,300 of the 15,000 acres remaining today. Its 1,000-acre Los Machos mangroves constitute one of the largest remaining mangrove forests on Puerto Rico. Studies have shown that overwintering Northern Waterthrushes move to thick stands of red mangrove with open water to roost overnight and then return to drier, differently structured mangroves to forage during the day. These studies generally show that resident and migrant species rely on mangroves more heavily than other habitat types, underscoring the significance of maintaining the diversity of mangrove forest types for migrant, as well as resident, bird species.
The former Navy range on Vieques Island hosts excellent scrub (thick thorn, forest, and evergreen) and mangrove forest (white, red, black, and button) communities. The avian diversity includes eight endemics among the 40 resident species, as well as a dozen wintering neotropical migrants. This former range is being incorporated into the USFWS National Wildlife Refuge system.
Cuba’s exceptional biological value can be measured by its high number of endemic plants and animals. The creation of Naval Station Guantanamo Bay in 1903 resulted in the preservation of exceptional habitat for many of these species, some of which are endemic to either Guantanamo or Cuba and are declining elsewhere. A rapid ecological assessment conducted by The Nature Conservancy found eight Cuban endemic bird species were abundant on the base, and significant stopover and wintering use by migrants. A follow-up multi-year, year-round study by The Institute for Bird Populations produced models for apparent survival for seven neotropical migrants and six endemics. This study led to the development of the MoSI program, now implemented throughout Latin America. Nearly 170 bird species have now been recorded on the base, including nine Cuban endemics.