Disappearing West Indian Seabirds

Introduction

The Caribbean Islands are considered one of the world’s “Biodiversity hot spots”, defined as an area of the planet that is critical to preserving the diversity of life on earth (Madre 1999). Twenty-five threatened regions were designated as hot spots by Conservation International, representing only 1.4% of the land surface of the world, but containing over 60% of all plant and animal species. These 25 areas also contain 81.6% of the world’s endangered bird species and high concentrations of endangered mammals and plants. All 25 areas have already lost 75% or more of their original vegetation. Five of the listed hot spots are tropical archipelagos: the Caribbean, Madagascar and the Indian Ocean Islands, Polynesia-Micronesia complex, New Caledonia, and Wallacea (Indonesia). This points out the severe conservation problems suffered in the islands today and the continuing loss of biodiversity. We hope in this publication, by presenting the status and conservation needs of West Indian sea birds, to draw attention to the ongoing declines in these populations and the need for immediate conservation action to preserve these species.

In the early 1980s van Halewyn and Norton (1984) and Sprunt (1984) summarized the status of and conservation issues for sea birds of the Caribbean region. Since then, more detailed inventories have revealed that, for a number of species, population estimates made at that time were too high, and in a few cases where population monitoring has occurred, dramatic declines in the number of reproductive pairs have been recorded. The original problems identified by van Halewyn and Norton (1984) have not been resolved (egg collecting, exotic predators, pollution, habitat destruction and disturbance) and several of them have become increasingly more severe over the last 15 years. Primarily because of the growing tourism industry, development of coastal habitats has increased and isolated cays and rocks, which were formerly relatively safe reproductive sites, are now being developed or are visited by tourists seeking remote island experiences. Ironically, the seabird colonies themselves are becoming attractions for the ecotourism industry. Presently most of the species of sea birds reproducing in the region are represented by tremendously reduced populations with aggregate numbers totaling only a few thousand pairs.

In August 1997, an International Seabird Workshop was held at the Society of Caribbean Ornithology's annual meeting in Aruba. Participants addressed conservation issues related to sea birds in the West Indies region and discussed steps needed to preserve seabird populations. All in attendance agreed that research and standardized monitoring had been largely neglected throughout the region, and that programs addressing these issues were vital to the long range survival of a number of locally breeding sea birds. Furthermore, with the general lack of seabird studies within the region, and resource manager's lack of familiarity with the status of various species, it was felt that a summary volume with detailed information on the species biology, distribution, conservation status and management needs was greatly needed. This publication is a direct result of these concerns. It represents the combined efforts of not only the authors of the chapters presented herein but also of a large number of biologists residing in the greater West Indies region.

The Bahama archipelago, Greater and Lesser Antilles, and Trinidad and Tobago (hereafter the West Indies region) support an important assemblage of breeding sea birds. In former times, the relatively predator-free islands of the region sustained much more abundant seabird populations which were probably ten times or more greater than those of today (Pregill et. al 1994). Human habitation of the islands started about 7,000 years before the present and evidence suggests that the initial impact on reproducing sea birds was devastating. With the arrival of man, sea birds became a common, easily obtained source of food, as evidenced by dumping-grounds on St. Croix, the Bahamas, and elsewhere (Palmer 1962, Steadman et al. 1984, Pregill et al. 1994, Steadman 1997, Wetmore 1938). This exploitation was followed by a period of European contact where human predation on sea birds and their eggs continued, and continues today, but to a lesser degree. A variety of introduced mammals compounded the problem. This not only includes mammalian predators but over grazing by feral goats and sheep which is causing major erosion problems on some islands. Generally, sea birds were driven from reproducing on the primary islands where human habitation and exotic mammal associates had taken over. For the most part, seabird colonies are now restricted to off shore rocks and cays, and inaccessible cliff zones.

It is difficult in modern times to fully appreciate the extent of pre-European contact, human reliance on seabird populations as a source of food in the West Indies. They provided an excellent, easily obtainable source of protein that was extensively exploited. The loss of sea birds from tropical islands is estimated to be about 90 to 99% (Pregill et al. 1994, Steadman 1985, 1989, 1995). In some cases, single species became a primary source for subsistence hunters and continual collecting over many years greatly depleted them. The following quotes from the 1600-1700s illustrate the extensive hunting of the Black-capped Petrel (Pterodroma hasitata), formerly an abundant species, but now in danger of extinction.

“It may be said that these birds are a manna that sends every year for negroes and for the lowly inhabitants, who do not live on any thing else during the season. After two or three hours of hunting I returned with my Negro to rest to cook some birds for dinner. I began finally to hunt alone. We reassembled at midday. The four Negroes had 138 diablotins. Albert had 43, and I had 17. Each of us ate two, and we left carrying the rest of our game.“
"Those who read these memoirs will doubtless be surprised that we should eat birds in Lent; but the missionaries who are in these islands, and who in many matters exercise the power of bishops, after serious deliberation and consultation of a medical man, have declared that lizards and diablotins are vegetable food, and that consequently they may be eaten at all times (Labat 1724).”
“Its flesh is so delicate that no hunter ever returns from the mountain who does not ardently desire to have a dozen of these "devils" hanging from his neck (du Tertre 1654).”

Most tropical sea birds in the West Indies now exist at modest to relatively low densities. They normally feed at sea at great distances from breeding sites, and typically produce just one slow-growing chick per year. The combined result is that sea birds are more vulnerable on their breeding sites than most land birds because of the protracted period of nest occupancy and the concentration of complete regional populations to a few sites. Furthermore, populations are slow to recover from disturbance because of their low reproductive output. The entire populations of most sea birds reproducing in the Caribbean consist of only several thousand pairs. To put the size of these populations in perspective with those in other regions, we point out that if all West Indian species were combined, the number would represent less than 20% of the total number of Leach's Storm-Petrels (Oceanodroma leucorhoa) from an only 6.3 sq kilometer reproducing site off eastern Canada (Sklepkovych and Montevecchi 1989). In fact, of the 21 species of sea birds reproducing in the West Indies, over half of these represent small populations whose conservation status is of current concern. Many of these are endemic species or races, and several are species with all or the majority of the world's population residing in the West Indies (see chapter “Action Plan for Conservation of West Indian sea birds”)

The Current Fauna

The breeding seabird fauna of the West Indies consists of three Procellariiformes (one of which, the Jamaican Petrel [Pterodroma caribbea] is possibly extinct, and another the Black-capped Petrel [P. hasitata] is highly endangered), seven species of Pelicaniformes (pelicans and their relatives) and 12 Laridae (gulls and terns). The Jamaican Petrel and Black-capped Petrel, Audubon's Shearwater (Puffinus lherminieri), White-tailed Tropicbird (Phaethon lepturus), Brown Pelican (Pelecanus occidentalis), Cayenne Tern (Sterna eurygnatha) and Bridled Tern (Sterna anaethetus) are all represented by endemic subspecies. The Roseate Tern (Sterna dougallii), is regarded as threatened by the US Fish and Wildlife Service with perhaps as much as 40% of the world's population breeding in the West Indies.

Nomenclature in this publication follows the American Ornithologists’ Union Checklist (1998). Of a total fauna of 21 seabird taxa reproducing in the West Indies (Table 1), 6 are endemic (Black-capped and Jamaica Petrel, Audubon’s Shearwater, White-tailed Tropicbird, Brown Pelican and Cayenne Tern [subspecies of Sandwich Tern]). Five species and one subspecies (>20 %) are considered to be “Critically Endangered”, 3 species are “Endangered”, 4 species “Vulnerable”, and 2 species “Near Threatened”. Studies of the subspecific descriptions of most of these species have not been conducted and one or more of them could represent unique subspecies given the lack of inter-island movement of the populations. Fourteen of the 21 species reproducing in the region are of conservation concern.

The Problems

Conservation of Caribbean sea birds has largely been overlooked. Most global assessments of areas said to be important to sea birds have been based on density and biomass figures, yet in the West Indies region sea birds were apparently so depleted prior to European contact and further depleted during the colonial period, that inventories are unavailable for primal populations. Because previously large populations of sea birds were not well documented in the literature, declines in West Indian species have not received the same amount of attention and concern as have some temperate and boreal sea birds. The serious conservation issues today are the continuing series of single event destructions of the small, seemingly unimportant relict colonies that remain. This site by site destruction has been spread out over time, not focused in any particular West Indian nation, or on any specific species, and for the most part is poorly documented.

Another problem, which has hampered seabird conservation, is that historically, ornithology in the West Indies region has focused on land bird studies, particularly on the zoogeography and conservation of island endemics. sea birds of the region have been neglected over the years. Moreover, because sea birds now typically are confined to remote areas, where it is difficult or expensive to conduct research, little work has been done on them. As a result we have little knowledge about the status of most sea birds, and even less knowledge about their local natural history. This makes developing conservation criteria for them difficult. If we are to preserve sea birds in the West Indies, we must develop long-term plans for basic research and conservation and implement them in a regionally consistent manner.

The rapid economic growth of the entire area jeopardizes even the remote areas where sea birds now restrict their reproducing activities. Growing tourism and other development in the Caribbean is directly threatening many remaining reproducing colonies. Seabird reproducing islands often have the exact characteristics desired by tourists seeking remote, isolated tropical retreats. In many cases the beauty and wildlife of the area draws tourists, but in the case of reproducing sea birds, because of their intolerance of human disturbance, tourist's visits can easily destroy the resource they come to see. The increasing number of charter boats has brought man and his pets into repeated contact with isolated seabird colonies with devastating effects. Based on the timing of visits as it relates to the phenology of particular colonies, even a single visit by people unaware of the needs of sea birds can destroy an entire year's production of the colony.

This scenario is made grimmer by the fact that there has never been a complete inventory of the sea birds in the Caribbean and there have only been a few continuing studies of specific sites available to show population trends. Some important reproducing sites believed to be of paramount importance to the regional survival of species have not been inventoried since the 1950s. Others have not been inventoried since the last century (Navassa Island, Cay Verde, Santo Domingo Cay, and others). Assessments made during the last 15 years (papers presented herein) show that the earlier inventories (van Halewyn and Norton 1984, Sprunt, 1984) erred in over-estimating populations. Additionally, populations of some species have declined dramatically during the past 15 years. Because the local populations are small, and condensed, the potential for the rapid disappearance of the few remaining major reproducing colonies is alarming. The ability of tropical species with modest reproductive output to colonize or re-colonize areas once destroyed is minimal. Recolonization may not even be an option. Recent data show that, in some areas, sea birds rarely move between islands (Schreiber and Schreiber 1988). There are many examples of massive losses of sea birds from tropical island groups around the world (Steadman 1985, 1989, 1995; Wragg and Weisler 1994) and far too many examples of local destructions and declines of species from particular islands in the Caribbean (Steadman et al. 1984, van Halewyn and Norton 1984 and papers in this volume).

Diversity in the Caribbean avifauna will be difficult to retain because of ecological imbalance and rapid development in a region with limited sources of income. Steps must be taken immediately to identify and protect areas important to sea birds. Local inventories and monitoring programs are greatly needed, but data gathering must be coordinated across the entire region. The difficulty in coordinating local inventories and long-term protection is exacerbated by the region's large number of independent political units (including mainland margins of the Caribbean, 28 different nations govern the region), languages, and currencies.

sea birds will provide a valuable, natural ecotourism resource if they and tourists can be properly managed. Also, as a top-level predator of marine food chains, they provide us with a valuable yardstick to monitor the general health of oceanic systems. For example, sea birds collected off the North Carolina coast (many of which are of West Indian origin) have been used to document baseline mercury loads in the tissues of 27 species (Whaling et al. 1980), and growing incidence of plastic ingestion by pelagic species (Moser and Lee 1992). Yet, within the West Indies region we know very little about key foraging areas or seasonal variations of surface productivity and how they relate to the locations and success of seabird colonies. Coastal development and source pollution in wet lands throughout the Caribbean region is damaging marine nursery grounds. Some sea birds feed in these nursery grounds but more importantly they support the young of prey species, contributing to the productivity of pelagic habitats. Destruction of these wet lands, and the disruption of the natural processes which support them, will not only severely harm marine bird populations, but will also harm the marine related economies of the region.

While the number of endangered and threatened species of sea birds in the West Indies paints a rather bleak picture, there are several important regional conservation efforts which have been successful.
Gochfeld et al. (1994) review case studies of five successful management programs :
1) Culebra, a Caribbean National Wildlife Refuge managed from Puerto Rico,
2) Desecheo, an island off Puerto Rico where exotic mammals are being eradicated,
3) Jamaica with a successful seabird management program,
4) Aruba where enforcement of existing wildlife laws, colony patrols and positive media coverage has allowed important larid colonies to recover.
5) Barbuda, after a training program for wardens and tour guides, has set up a very successful eco-tourism program for their Great Frigatebird colony.
These regional programs each serve as successful models that can be used elsewhere in the region. Consultation with the countries that have carried out successful programs can assist other countries in developing similar plans.

Birds' Table

The chapters that follow are an outgrowth of a symposium held in Aruba at the annual meeting of the Society of Caribbean Ornithology in August 1997. During the meeting, seabird biologists and persons responsible for environmental programs from the West Indies and Bahamas were charged with estimating regional population sizes and developing of conservation priorities for the 21 species of reproducing sea birds in the region. The general consensus of the participants was that seabird populations of the West Indies are lower than previously believed and that a number of species were of serious conservation concern. At that time West Indian sea birds were grouped into four conservation priority levels using the basics of the criteria developed by the International Union for the Conservation of Nature (see Chapter “ Action Plan for Conservation of West Indian sea birds”). The status review papers in this volume support these species priority ratings.

Table 1. Species list for West Indies and number of reproducing pairs. SaintnMartin : = Nest on island, = Unseen here,
Common Name	Scientific Name	Number of Pairs
Cahow Petrel Jamaica Petrel Black Noddy CayenneTern Common Tern Gull-billed Tern Royal Tern Masked Booby Black-capped Petrel Brown Pelican Least Tern Red-billed Tropicbird Sandwich Tern White-tailed Tropicbird Audubon’s Shearwater Roseate Tern Magnificent Frigatebird Bridled Tern Laughing Gulls Brown Booby Red-footed booby Brown Noddy Sooty Tern	Pterdroma cahow Pterdroma caribbea Anous tenuirostris Sterna s. eurygnatha Sterna hirundo Sterna nilotica Sterna maxima Sula dactylatra Pterdroma hasitata Pelecanus occidentalis Sterna antillarum Phaethon aethereus Sterna sandvicensis Phaethon lepturus Puffinus lherminieri Sterna dougallii Fregata magnificens Sterna anaethetus Larus atricilla Sula leucogaster Sula sula Anous stolidus Sterna fuscata	now extinct in region 0-15 fewer than 100 10-100 50-100 100-500 450-800 550-650 1000-2000 1500-2800 1500-3000 1800-2500 2100-3000 2500-3500 3000-5000 4000-6000 4300-5300 5000-7000 5000-10 000 5500-7800 8200-10 000 10 000-18 000 200,000-300,000

The Papers in this Volume

This volume is designed to serve as a guide to Caribbean nations in identifying regional seabird conservation issues and as a base line against which to measure long-range population trends of individual species. The volume also provides the necessary information to assist Government environmental managers in making the beginning steps toward conservation of sea birds. The chapters address the population status and conservation concerns for each reproducing seabird species in the West Indies. sea birds reproducing in Mexico and along the Caribbean coasts of Central and South America are not covered specifically in this volume. Some authors do make a few brief comments about these areas for reference. In many cases, the current status of key colonies is unknown, and in a number of instances there have been no reports from colonies in the past 100 years. Where the data exist, we have tried to present details on exact colony locations as much as possible for comparison to future monitoring efforts. The distribution maps for each species are generated from a GIS system (see chapter on this by W.Mackin) and new information can be entered into this database as it becomes available.

E. A. Schreiber provides a chapter outlining current research needs for the region and a summary chapter discussing conservation priorities, listing species with ranking by degree of concern, and making recommendations for needed conservation action. A chapter outlining appropriate monitoring techniques is provided by Alan Burger. Paul and Francine Buckley discuss the use of helicopters to assess the status of sea birds over a large area. Also included is a complete bibliography of the sea birds of the region prepared by Jim Wiley. It is our hope that this volume will become a valuable resource for those working in the region who do not have access to much of the primary literature and that it will serve as a guide to the development of conservation action plans for the West Indies.

Acknowledgements

We thank the Society of Caribbean Ornithology and its members who have worked hard to provide data on the sea birds in their area and those who have written chapters for this publication, and the U.S. Fish and Wildlife Service for their support of the SCO and its annual meetings. We thank RAMSAR (Gland, Switzerland) and Seabird Research, Inc.(Alexandria, VA, U.S.A.) for providing funding to publish the results of this symposium. We are indebted to Will Mackin, Univ. of North Carolina who prepared the maps.

Literature cited