Bahamas: Little San Salvador

After a day at sea, our ship reached its final new port on Friday April 10: The tiny island of Little San Salvador in the Bahamas. The island, which lies not far from the long, serpentine island of Eleuthera, is wholly owned by Holland America Lines. "Little San Salvador" isn't a terribly romantic name, so Holland America has renamed its property "Half Moon Cay". It took me a bit of research to find out the real name of the place. I'm not an employee of Holland America, so, Dear Readers, it'll be Little San Salvador on this blog.

Most of the cruise passengers never get past the shops just off the dock. That didn't include Eileen and I, of course, though the heat of the day did control our movements somewhat!

Fortunately, the good folks at Holland America (or someone) have provided a genuine Nature Trail for us to follow. Little San Salvador is protected, I am happy to say, as a Wild Bird Preserve, and its brackish interior lagoon has been designated as an important wetland by the Bahamas National Trust.

On the narrow, sandy strip between the island's south shore, where Holland America lands its passengers, and the interior lagoon, many of the plants are typical coastal species adapted to dealing with salt spray. This is a morning glory, one of a dozen species of the genus Ipomoea in the Bahamas -- almost certainly Ipomoea pes-caprae, the beach morning glory, a highly salt-tolerant species found on tropical beaches around the world. "Pes-caprae" means "goat's foot", and the cleft, two-lobed leaf does suggest a goat's hoof at least.

Nonetheless, as this and the next two photos show, the island is far from treeless; there is some genuine woodland, known as coppice, on the north shore, but it was out of reach for us. On the south shore the vegetation is sandy scrub, with a few emergents like these palms (I assume they are some sort of thatch palm (Thrinax) but I would be glad to be enlightened further!)

The scrub itself is pretty dense stuff, similar to the sort of thing you can see in the Florida Keys, with an undergrowth heavily laced with saw palmetto (Serenoa repens). It is, of course, bird habitat, and though it is not a rich as the coppice woodlands of the larger islands it still holds a few "Bahama specialties". Robert L. Norton reported 42 species from Little San Salvador (Fla. Field Nat. 21(1):16-17 (1993)), 36 of which he saw himself in a few hours. Probably only seven or eight of them, though, are land birds that actually breed there. For a visiting birder off a cruise ship, it is a question of quality, not quantity!

Here, singing away, is a Thick-billed Vireo (Vireo crassirostris), a bird missing from Norton's list. Finding it here should not be a surprise; it is widespread in the Bahamas. This is a species with a most peculiar range: it seems to be a small island specialist, missing from the larger land masses of the Antilles but present on a few widely scattered islets. Besides the Bahamas, it lives on the Caicos and the Caymans, but is only a rare stray to Cuba and South Florida. A population of vireos on the distant island of Providencia in the far southwest Caribbean was once also thought to be this species, but according to my graduate supervisor, and leading vireo expert, Jon C. Barlow (who, sadly, passed away recently), the Providencia birds are actually Mangrove Vireos (V. pallens).

Even more interesting are the ubiquitous Bananaquits. Bananaquits, of course, are widespread in the West Indies and indeed have a huge range in Central and South America. Nowhere, though, do they look the way they do in the Bahamas (compare the bird in these photos to the Virgin Islands Bananaquit in my last blog entry). You could be forgiven for thinking these almost entirely black-and-white little birds, patched with yellow on the chest, belonged to a different species altogether from their primarily grey-and-yellow, dark-throated compatriots elsewhere in their range.

The truth, apparently, is more interesting. You can read all about it in a study published in 2008, "The dynamic evolutionary history of the bananaquit (Coereba flaveola) in the Caribbean revealed by a multigene analysis" by Eva Bellemain, Eldredge Bermingham and Robert E Ricklefs (BMC Evolutionary Biology 2008, 8:240). It appears that the various populations of Bananaquit have a complex evolutionary history, involving a number of island-hopping colonizations and invasions.

Most island birds originally reached their homes from the mainland, but Bananaquits (or so their DNA tells us) actually evolved in the Bahamas and the Greater Antilles (their closest relatives, oddly enough, appear to be grassquits and West Indian "bullfinches"), and spread to the rest of their range, including the mainland, from there. The Bahamas birds apparently split from most of the others about 1.75-3.99 million years ago, but, oddly, they have genetic similarities to birds from islands off the Yucatan Peninsula (such a Cozumel) that otherwise look like "typical" birds from other areas. There are no Bananaquits on Cuba, which lies between the Bahamas and Mexico; were they there once, long ago -- and if so, what did they look like?

All this matters very little, of course, to a naturalist simply enjoying being among bold, tame birds with lots of personality. For that, one species even beats the Bananaquit: the Bahama Mockingbird (Mimus gundlachii) -- another bird with a peculiar range, by the way; other than in the Bahamas (and occasionally Florida, where I saw one in Key West many years ago), it shows up again in the dry southwest of Jamaica.

Bahama Mockingbirds are duller and streakier (though larger) than the Northern Mockingbird (M. polyglottos) so common in nearby areas like Florida and Jamaica, but is none the less charming for that.

On Little San Salvador, they are noisy and bold, and take full advantage of cruise visitors.

This one is checking us out at a picnic table, waiting to see if we will drop any tasty scraps. The birds will hop right onto the table to get them - behaviour which, I am sorry to say, annoyed some of our fellow passengers. Not all cruise passengers, alas, are naturalists.

And with that, I come to the end of our cruise -- a week-long trip that it has taken me seven months to get around to writing up. It' a sad thing, I know, when our lives conflict with or blogging duties -- I'll have to do better in future....!