Faculty: William K. Hayes
Laboratory of behavioral ecology and conservation
We have good reason to be concerned about a number of Bahamian bird taxa. Because some live on just one or a few small islands, their populations are perilously small to begin with. Moreover, some may have diverged more from close relatives than currently recognized, and these may be distinct, previously-unrecognized species.
The idea for the projects described here came to me while I was sitting in an Important Bird Areas Workshop for the Bahamas. It was a warm, humid day in April, 2002. A group of ornithologists, birdwatchers, and government and NGO conservation officials (including Birdlife International) had gathered at The Retreat, headquarters of the Bahamas National Trust, to discuss and plan priorities for conserving the best remaining bird habitats in the Bahamian archipelago.
As the two-day workshop progressed, I grew frustrated with the discussion returning, time and time again, to the fact that we simply don't know much about the birds in the Bahamas. For many species, we have at best only a vague idea as to how many remain, and how their relative abundance varies from island to island. And remarks were often made that certain island forms might in fact be distinct but currently unrecognized species. Clearly, if an island form was a distinct species, and it was now in trouble, we would be amiss not to prioritize protecting its habitat.
So I asked myself, as a scientist, what would be the most valuable contribution I could make to help preserve some of the natural history and birdlife of this wonderful island nation? The answer seemed clear: I needed to use some of the statistical tools I had recently learned (from my iguana research) to do a taxonomic evaluation of those forms most likely to represent distinct-and critically endangered-species.
I quickly wrote up a list of potential candidate species and, before I knew it, I was waist deep in a handful of projects. These projects reflect my desire to study taxonomy from a conservation perspective. The question of species status is important considering the paradigm most frequently used in setting conservation priorities. Conservation authorities confer highest priority to evolutionarily significant units (ESUs), which are, in essence, full species. Even so, subspecies and genetically-distinct populations can receive a lower priority status, that of management units (MUs). Because saving endangered species requires saving habitats, publicity resulting from high-profile endangered animals, such as endemic birds, can offer a reprieve for these habitats. Taxa that capture the public's attention are often called "flagship species." Birds seem better suited for this than most other groups, such as amphibians and reptiles.
We have good reason to be concerned about the future of these and other Bahamian birds. The pressure to transform island landscapes escalates further with each passing year. Developers are eager to bulldoze more and more sensitive habitats. The recent flurry of hurricanes (likely to continue for a few more decades) can also inflict damage to remaining habitats. Thus, our efforts to identify critically endangered island species are, in a real sense, a race against time. We hope that our findings, whatever they are, can help to save a few unique birds and their fragile habitats.
James Bond, licensed to kill... Birds, that is. Yep, the real James Bond was an ornithologist (note the labels above). Ian Fleming, who created the James Bond character, actually took the name of his spy character from the highly-respected Philadelphia Academy of Sciences ornithologist. Birds collected for science, often more than 100 years ago, offer an invaluable means of assessing conservation (taxonomic) units and, hence, prioritizing limited funds for preserving critical habitats. Photograph: William K. Hayes.
Project 1: Conservation Taxonomy and Population Status of the West Indian Woodpecker Complex
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.
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.
In the Bahamas, the woodpecker is common on Abaco, rare on San Salvador Island, and thought to be extirpated on Grand Bahama. A pair seen recently on the east end of Grand Bahama (2002-2004) may be good news for the Grand Bahama form but more likely represents a colonizing pair from Abaco. Unfortunately, these birds have not been seen again since the hurricanes in September 2004. The species is also common and widespread on Cuba and its offshore cays, on Isle of Pines (Isle of Youth), and on Grand Cayman Island. A few strays have been recorded on the other Cayman Islands.
According to Raffaele et al. (1988, A Guide to the Birds of the West Indies, Princeton University Press), this bird occupies primarily dry forests, scrub, forest and swamp edges, coastal forest, and palm groves. On Abaco, it inhabits settled areas. It breeds from January to August (but later, from May to August, in the Bahamas), nesting in a tree excavation and often producing more than one brood. Although most pairs are probably monogamous, classical polyandry (female mating multiple males) has been reported (Willimont et al al., 1991, Wilson Bull. 103:124-125).
Living jewels of the Bahamas. West Indian Woodpeckers from Abaco (left) and San Salvador Island (right). Both birds are males. Although the woodpecker remains common on Abaco, it is now rare on San Salvador and apparently extirpated on Grand Bahama. Photographs: Bruce Hallett.
Grand Cayman form of the West Indian Woodpecker. Note the striking coloration of the male (left), which lacks the black eye patch that is present on all other forms of the woodpecker. This form also exhibits very pale nasal tufts and reduced black on the back with a deep suffusion of gold. As in other West Indian Woodpeckers, the smaller female (right) lacks red on the crown. Photographs: Bruce Hallett.
To evaluate the taxonomic validity of the six recognized subspecies, I am taking morphological measurements of specimens borrowed from various museum collections. To evaluate our data, we rely on a statistical procedure called Discriminant Function Analysis. This test considers the variance in a set of characters and then objectively assigns (or diagnoses) each individual to a defined (taxonomic) group. If two different populations are considered, for example, and at least 75% of the individuals within each can be correctly assigned by this procedure, then the two groups would be considered distinct enough to represent separate subspecies based on the 75% diagnosis rule (Patten and Unitt, 2002, Auk 119:26-35). If there was 100% diagnosis of both groups, they could be regarded as separate species (though species definitions vary considerably and can be highly problematic).
Our preliminary data suggest that several species might exist within this complex (see figures below).
Museum specimens of West Indian Woodpecker. Note the obvious difference in overall size (all males). The three Bahamian forms (left), with mostly black-and-white backs, are substantially smaller than the more golden-backed Cuban form (fourth from left). The Isle of Pines form (fifth from left) is somewhat smaller than the Cuban form, and the Cayman Island form is smaller yet (furthest right). The Cayman Island form has the least black and most gold on the back. Photograph: William K. Hayes.
Representative males of the six recognized subspecies. The San Salvador Island form (M. s. nyeanus) has very dark nasal tufts and substantially less black around the eye; it may be distinct from the Grand Bahama (M. s. bahamensis) and Abaco (M. s. blakei) forms. South of Cuba, the smaller Isle of Pines form (M. s. murceus) is probably a subspecies of the Cuban form, whereas the Grand Cayman form (M. s. caymanensis) completely lacks black around the eye and may be a distinct species. Thus, as many as four species might exist in this complex...but more work is needed. Photograph: William K. Hayes.
How to quantify size of black eye patch? My graduate student, Tim Revell, offered a brilliant solution. Use a transparent plastic grid and count the squares. The Cuban form (left) has a large patch, whereas the San Salvador Island form (right) has a very small patch. Photographs: William K. Hayes.
Most importantly, if the San Salvador, Bahamas, form is a valid taxon, it would be one of the rarest birds in the world. In the 1970s, Robert Miller (1978, Auk 95:281-287) estimated that 100-160 pairs remained. My own recent surveys (2004) support this conclusion, but surveys in 2005 suggest that the population was hit hard by Hurricane Frances, a category 4 storm that passed directly over San Salvador in September, 2005. Obviously, a recovery program would need to be developed if this bird is, indeed, a valid subspecies or species. Hopefully, much of its remaining habitat can be spared the bulldozer. But sadly, there is increasing pressure to develop further the fragile habitats that remain on San Salvador Island. This bird needs some serious attention!
Stay tuned for more results and conclusions...
Project 2: Conservation Taxonomy and Ecology of the Bahama Nuthatch
The Brown-headed Nuthatch (Sitta pusilla) dwells in pine forests throughout much of the southeastern United States and on one island (Grand Bahama) in the Bahamas. It is closely related to the Pygmy Nuthatch (Sitta pygmaea), which inhabits pine forests in western North America.
Grand Bahama race of the Brown-headed Nuthatch (Sitta pusilla insularis). Does the population on Grand Bahama constitute a distinct species? Photograph: Gary Slater.
This adorable bird exhibits several highly unusual behaviors. It is one of the very few North American species that exhibits cooperative breeding, in which young males assist with nest construction, nest sanitation, and feeding of the female, nestlings, and fledglings. It is also one of very few birds known to use a tool. On occasion, it uses a bark chip to pry off other bark chips during foraging. Like the other North American nuthatches, it frequently forages upside-down.
At present, three subspecies are recognized:
Sitta pusilla pusilla - this continental form is found throughout much of the southeastern United States, from New Jersey to Georgia on the coastal plain and west to extreme southeastern Oklahoma and eastern Texas.
Sitta pusilla caniceps - this second continental form is limited to Florida (all but the far west portion of the panhandle) and extreme south Georgia. It sports a slightly grayer head, smaller body size, and larger bill, but its taxonomic status remains debatable.
Sitta pusilla insularis - this insular form is restricted to Grand Bahama Island in the Bahamas. Remarkably, its taxonomic status was based on the examination of only three specimens. The relatively long bill, short wings, and darker loral and auricular plumage were considered distinct enough to warrant subspecies status. It also shows more white on the chin and belly and has a somewhat different voice.
Viva la difference! At present, three forms of Brown-headed Nuthatch are recognized: Sitta p. pusilla (much of southeastern U.S.), S. p. caniceps (Florida), and S. p. insularis (Grand Bahama). Representative adults of the Florida (left) and Bahama (right) forms are shown. Note the obvious difference in bill size, though there appears to be slight overlap in this character. Recently, we have proposed elevation to full species of the Bahamas form, based largely on vocal differences. Photograph: William K. Hayes.
Because of extensive logging and substantial alteration of pine forests in the last century, populations are declining throughout its range. This problem has been most critical for the Grand Bahama subspecies. Twenty years ago, the bird was quite common and easily found within its Caribbean Pine (Pinus caribaea) habitat. In the last few decades, only one or two individuals have been reported each year. Obviously, we need to learn more about this bird before it disappears altogether. Is it indeed a valid subspecies? Or could it even be a full species?
After detailed morphometric analyses of museum specimens, it became clear that the Bahamas taxon was fairly distinct from the U.S. forms - though perhaps not sufficient for elevation to full species. Curiously, the Bahama Nuthatch looks very similar to the Brown-headed Nuthatch, but structurally it is more different from the Brown-headed Nuthatch than is another distinct species, the Pygmy Nuthatch.
Fortunately, these data helped us acquire a small grant from the Grand Bahama Power Company to conduct fieldwork in the Bahamas during July 2004. After a very discouraging and unproductive first week of surveys, during which we encountered no nuthatches whatsoever, my co-researchers and I finally stumbled upon a small group of the sought-after birds. To our astonishment, one of their primary vocalizations was unlike any Brown-headed Nuthatch we had heard previously in North America. By using taped playback of the bird's unique "warble" vocalization, we were able to better locate additional groups of nuthatches. Thus, by the end of the summer, we confirmed that a viable population of nuthatches remains on Grand Bahama. However, we also estimated that fewer than 1,000 individuals likely remain. Continued field work in 2005 failed to give a reliable estimate of numbers, but it was clear that the population declined as a consequence of the two major hurricanes (Frances and Jeanne) that passed over Grand Bahama in September, 2005.
More exciting perhaps, we have proposed that the Grand Bahama population warrants elevation to full species, largely on the basis of its unique vocalization (the "warble" call). If our proposal is accepted by the American Ornithologists Union, the Bahama Nuthatch would represent the fourth endemic bird species in the Bahamas, joining the Bahama Woodstar (a hummingbird), the Bahama Swallow, and the Bahama Yellowthroat (a warbler). It would also be among the rarest bird species in the world.
Spectrogram of the distinctive Bahama Nuthatch vocalization. You may listen to or download this unique call (.wav - 768 K). Spectrogram from Hayes et al. (2005), Bahamas Journal of Science 12(1):21-28. PDF reprint (366 K).
As a distinct, highly-endangered species, this bird requires immediate management. Research will be essential to answer important questions. How many birds truly remain? What has caused its recent demise? Can it survive in the face of non-native competitors [e.g., the cavity-nesting European Starling, Sturnus vulgaris] and predators [e.g., Corn Snake (Elaphe guttata), Raccoon, (Procyon lotor), Black Rat (Rattus rattus)]? How can the population be increased? Will it benefit from a nest box campaign? Will controlled burning of the pine forest be necessary? Can land be set aside to preserve it? Where can we find the funds to conduct these studies?
Gary Slater of Ecostudies Institute has joined us in our studies of the nuthatch. In April, 2005, he managed to mist-net a single nuthatch for eventual DNA work and he also located two active nests approximately 10 m above the ground in pine trees. Nesting high above the ground is a trait similar to that of Florida birds, as populations elsewhere tend to nest much closer to the ground.
We'd like to thank the Grand Bahama Power Company for their generous support of our research. Without this company's insight and commitment to environmental causes, our field studies and the discovery of this bird's unique vocalizations would not have been possible. We can only hope that other organizations in the Bahamas will eventually recognize the importance of corporate-sponsored conservation programs. Such support can truly can make a difference.
Project 3: Conservation Taxonomy and Population Status of the Bahama Oriole
The Greater Antillean Oriole (Icterus dominicensis) occupies four major island groups: the Bahamas, Cuba, Hispaniola, and Puerto Rico. However, each population has a distinctive plumage and some have speculated that multiple species are represented by the group. Could the remaining population in the Bahamas (I. d. bahamensis) be a distinct species?
More details of our research will be uploaded shortly.
Project 4: Conservation Taxonomy of the Cuban Parrot
Presently, five subspecies of the Cuban Parrot (Amazona leucocephala) are recognized. These occur in the Bahamas (A. l. bahamensis), on Cuba and the Isle of Pines (A. l. leucocephala and A. l. palmarum), on Grand Cayman (A. l. caymanensis), and on Cayman Brac (A. l. hesterna). Could the populations in the Bahamas represent distinct species?
More details of our research will be uploaded shortly.
Project 5: The Calm After the Storm - Impact of Hurricanes on Grand Bahama's Pine Forest Birds.
In September of 2004, two catastrophic storms passed directly over Grand Bahama's pine forests. Hurricane Frances struck on September 4 with 90 kt (104 mph) winds. Hurricane Jeanne arrived on September 25 with 105 kt (121 mph) winds. How did these storms affect the birdlife on Grand Bahama? You might be astonished to learn just how severe the impact was...
More details of our research will be uploaded shortly.