Birds

Seabirds  |  Land Birds 

San Salvador’s Seabirds

Brown Boobies Photo William K Hayes

The fragility of San Salvador’s seabird populations can be better appreciated from a broader perspective. Globally, seabirds are declining at an alarming rate. 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 occupancy because of slow chick growth, and slow maturation. As a consequence, seabirds are slow to recover from population declines. Increased development of coastal sites exacerbates the primary threats, which include habitat destruction, colony disturbance, exotic predators, pollution, and egg collecting. The diversity and sheer number of seabirds nesting in the Bahamas exceed that of any other nation in the West Indies region. Nevertheless, while San Salvador’s populations appear to be healthy, dramatic declines have been documented in other regions of the Bahamas.

By virtue of their high agility, the Bahamas’ wealth of seabirds is truly an international resource. Outside their breeding season, a number of species disperse great distances, some as far as Africa. Conversely, many seabirds that breed elsewhere migrate through or forage seasonally in Bahamian waters. Clearly, healthy foraging and nesting sites within the Bahamas are critical for the survival of many seabird species.

Seabird conservation may not be as simple as one might think. The most obvious resource to protect would be existing nesting sites. Unfortunately, seabirds frequently colonize coastal habitats that are prized by humans for their real estate or recreational value. Though much less well understood, productive foraging sites are also critical for survival. Some species forage far out to sea, whereas others rely on coastal wetlands. Coastal development and pollution disrupt natural processes and damage important marine nurseries that may be critical for early development of both near-shore and pelagic prey species. Impacts may extend far beyond coastal wetlands, and threaten not only the seabirds but also marine-related economies. Numerous examples, often involving massive population losses, illustrate the consequences of failure to provide adequate protection for seabirds and their habitats.

A number of critical areas must be protected if San Salvador’s seabirds are to persist (see Map). Most important, Graham’s Harbor and its offshore cays (Catto, Gaulin, Green, and White Cays) presently support the largest colonies. More than a thousand pairs of ten species nest each year on these cays and on the main island bluffs. The eelgrass beds and coral reefs provide a rich nursery for sustaining their prey. Also important are Pigeon Cay in Great Lake and the adjacent islets to the immediate southeast. These support large colonies of double-crested cormorants, laughing gulls, and three or more heron species that thrive on the small fish inhabiting Great Lake. High, Middle, and Low Cays, at the mouth of Pigeon Creek, also support seabird colonies, though the largest colonies (sooty terns and brown noddies) have disappeared from here in recent years. Pigeon Creek itself provides a vital nursery for prey species. Finally, bluffs on the main island shoreline provide nesting burrows for Audubon’s shearwaters and white-tailed tropicbirds. Ideally, further development should be prohibited on any rocky shoreline.

For more information visit the website of William K. Hayes at Loma Linda University.

West Indian Woodpecker Photo Bruce Hallett

The West Indian Woodpecker (Melanerpes superciliaris) occupies six major Caribbean islands, representing a highly disjunct distribution (see map below). Although there is some disagreement, each island form is generally recognized as a distinct subspecies. The species or species complex is closely allied to, and probably derived from, the Red-bellied Woodpecker (Melanerpes carolinus) of the southeastern United States.

For more information about the West Indian Woodpecker visit the website of William K. Hayes at Loma Linda University.

 

 

 

West Indian Woodpecker Photo William K Hayes

 

 

 

Distribution of West Indian Woodpecker (Melanerpes superciliaris). The three Bahamian subspecies live on Grand Bahama (M. s. bahamensis), Abaco (M. s. blakei), and San Salvador Island (M. s. nyeanus). Three other forms (from north to south) live on Cuba (M. s. superciliaris), Isle of Pines (M. s. murceus), and Grand Cayman Island (M. s. caymanensis). Several additional subspecies have been described from isolated islands off Cuba (not shown here). Map: William K. Hayes.

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