Hayes, W. K. 2003. Can San Salvador’s iguanas and seabirds be saved? Bahamas J. Sci. 11(1):2-8. (reformatted from original) Can San Salvador’s Iguanas and Seabirds Be Saved? William K. Hayes, Ph.D. Department of Natural Sciences Loma Linda University Loma Linda, CA 92350 USA San Salvador Island’s remoteness and fecal material actually increases the viability of seeds isolation have created a haven for many animals that and seedlings. have declined or vanished elsewhere in the Bahamas. Even so, the impacts by humans have been severe. Iguanas are found elsewhere in the Bahamas Today, the island looks very different from what (Figure 1), but those on San Salvador are unique. Christopher Columbus saw in 1492 when he first They have no other home in the world. Sadly, their stepped onto its fine white beaches. The huge trees, decline has been staggering. At present, fewer than dragon-like iguanas, and vast flocks of parrots and 600 iguanas likely remain, and these are now seabirds, all of which the Lucayan Indians relied on restricted to a mere fraction (0.2%) of their former for sustenance, greatly impressed Columbus. range (Hayes et al., 1995, 2004). They are essentially However, the parrots and Lucayans disappeared soon confined to the most remote and inaccessible places afterward. Following the American Revolution, available: four tiny offshore cays and two small islets loyalist plantation-owners felled the majestic trees to within the hypersaline lakes (31.5 ha total; Figure 2). raise cotton, an endeavor that eventually was A few individuals are still encountered rarely on the abandoned. Fossil remains indicate that tortoises and main island (163 km2), but no viable population crocodiles once roamed the landscape as well (Olson remains. Three populations have become extirpated et al., 1990), though their disappearance may have in recent decades (Barn Cay in the 1970's, and High predated Columbus and perhaps even the arrival of Cay and Gaulin Cay in the 1990's). Since 1993, Indians roughly 2,000 years ago. Sadly, only the when we first began to study these populations, we iguanas and seabirds now remain—and these, too, have documented declines on other cays as well. could easily suffer the same fate. I have been privileged to study San Salvador’s iguanas and seabirds for more than a decade. My collaborators and I have grown increasingly worried about what the future holds for them. Called by some “The Forgotten Island,” San Salvador remains relatively pristine and undeveloped. However, whether we like it or not, the island’s fragile ecosystems will come under increasing pressure as development inevitably brings more residents, tourists, construction, pollution, and exotic species to the island. If the iguanas and seabirds are to persist, we must learn more about them and seek ways to protect the habitats and resources critical for their survival. San Salvador Rock Iguana (Cyclura rileyi rileyi) Figure 1. Distribution of Cyclura in the Bahamas, including the three subspecies of C. cychlura We know from the fossil record that the (Andros, northern Exumas, southern Exumas) and the main island of San Salvador formerly teemed with three subspecies of C. rileyi (southern Exumas, San iguanas. As the largest terrestrial vertebrates in the Salvador Island, Acklins Bight). Cyclura carinata Bahamas, iguanas contribute to the uniqueness and bartschi exists only on Booby Cay off of Mayaguana health of Bahamian ecosystems. As vegetarians, they Island, Bahamas; the second subspecies of C. distribute the seeds of plants in their feces, and the carinata occurs in the Turks and Caicos Islands to the south. A number of threats make continued habitats. We hope to eventually create new survival of the iguanas tenuous (Hayes et al., 1995, populations. Through an outreach program (Carter et 2004). They are especially vulnerable to feral al., 2003), we have brought their fragile existence to animals, including cats, dogs, and rats. For this the attention of San Salvadorans, who are eager to reason, the iguanas may never be able to re-colonize see the iguanas thrive and hopefully increase in the main island. Some of the remaining populations numbers. However, we are greatly concerned by the coexist with rats, and others have suffered vegetation threat of further development. Increased visitation by damage from recent catastrophic storms and the humans, their pets, or unintended stowaways (e.g., larvae of an introduced, cactus-eating moth rats, fire ants, non-native plants) will spell certain (Cactoblastis cactorum). Rising sea levels threaten doom. to inundate the lower-elevation cays. Disease could be catastrophic because of the small populations and The most critical populations to protect limited genetic diversity. In spite of strict protection include Green Cay (Graham’s Harbor) and Goulding by CITES (Convention on the International Trade in Cay (Green’s Bay); collectively, these islands harbor Endangered Species) and Bahamian law, humans still nearly two-thirds of the remaining iguanas. Because remove some of the iguanas. Two smugglers are the iguanas on Low Cay attain the largest size and presently in a United States jail for having done so! produce the largest clutches of eggs, they warrant protection as well. Unfortunately, only two These unique and majestic lizards (Figures populations (Green Cay and Pigeon Cay) appear to 3-4) still have a chance to survive. Based on more be on Crown Land; these would be the easiest to than a decade of research, we have a much clearer protect from future development. picture of their ecological requirements (Carter and Hayes, 2004; Hayes et al., 1995, 2004). Though our time and funds are severely constrained, we are San Salvador’s Seabirds working to safeguard and improve remaining Because of the island’s relatively pristine state, the seabirds of San Salvador are absolutely spectacular. The offshore cays, main island bluffs, and interior lakes support some of the largest breeding colonies of seabirds to be found in the Bahamas (Table 2). Remarkably, San Salvador hosts 14 (82%) of the 17 seabird species that breed in the Bahamas (some are pictured in Figures 5-11). This number does not include a pair of masked boobies that I observed courting but could not confirm nesting in 1998. The number of seabird species breeding here exceeds that of any other locality in the Bahamas (White and Lee, 2001). Eight of these species are of special concern because of declining numbers in the West Indies region and their vulnerability to extinction (White and Lee, 2001). For some species, such as Audubon’s shearwater and double-crested cormorant, a substantial fraction of the entire West Indies population breeds on San Salvador Island. The fragility of San Salvador’s seabird populations can be better appreciated from a broader perspective. Globally, seabirds are declining at an alarming rate (Schreiber and Lee, 2000). Approximately 20% of the world’s seabird species are threatened by extinction. The loss of seabirds on tropical islands due to human disturbance has been estimated at a staggering 90 to 99%. Several life history attributes render seabirds especially vulnerable. These include nesting in high density at few sites, small clutch sizes, prolonged nest Figure 2. San Salvador Island and its associated occupancy because of slow chick growth, and slow cays. maturation. As a consequence, seabirds are slow to Table 1. Population estimates (N) for San Salvador Island iguanas (Cyclura rileyi rileyi), with their present status and identified threats (data from 1993-2003). Cay N Status & Identified Threats Goulding 116-174 Stable; no known threats Green 130-195 Declining; hurricane damage, cactus die-off, smuggling by humans Guana 30-45 Increasing; recovery from mortality event in 1994, rats present Low 42-63 Declining; low survival of juveniles to adults, cactus die-off, rats present Manhead 38-57 Stable or declining; cactus die-off Pigeon 70-105 Stable or declining; hurricane damage, rising water levels, rats present Total: 426-639 Decline continues recover from population declines. Increased Unfortunately, seabirds frequently colonize coastal development of coastal sites exacerbates the primary habitats that are prized by humans for their real estate threats, which include habitat destruction, colony or recreational value. Though much less well disturbance, exotic predators, pollution, and egg understood, productive foraging sites are also critical collecting. The diversity and sheer number of for survival. Some species forage far out to sea, seabirds nesting in the Bahamas exceed that of any whereas others rely on coastal wetlands. Coastal other nation in the West Indies region. Nevertheless, development and pollution disrupt natural processes while San Salvador’s populations appear to be and damage important marine nurseries that may be healthy, dramatic declines have been documented in critical for early development of both near-shore and other regions of the Bahamas (White and Lee, 2001). pelagic prey species. Impacts may extend far beyond coastal wetlands, and threaten not only the seabirds By virtue of their high vagility, the but also marine-related economies. Numerous Bahamas’ wealth of seabirds is truly an international examples, often involving massive population losses, resource. Outside their breeding season, a number of illustrate the consequences of failure to provide species disperse great distances, some as far as adequate protection for seabirds and their habitats Africa. Conversely, many seabirds that breed (e.g., Steadman, 1997; Schreiber and Lee, 2000; elsewhere migrate through or forage seasonally in White and Lee, 2001). Bahamian waters. Clearly, healthy foraging and nesting sites within the Bahamas are critical for the A number of critical areas must be protected survival of many seabird species. if San Salvador’s seabirds are to persist. Most important, Graham’s Harbor and its offshore cays Seabird conservation may not be as simple (Catto, Gaulin, Green, and White Cays) presently as one might think.