These particular giants have now been largely eliminated due to the actions of conservationists and a flawed plan to capture them and maintain them on another island, where they starved.
Luckily the leading herpetologist was incorrect about the total amount iguanas on Allen's Cay, and those 'extra' lizards which evaded capture apparently survived their island being covered in rodenticide.
People often visit the two main islands which host the majority of the population, and the iguanas have come to expect to be fed by them, sometimes congregating on the beach in large numbers awaiting tourists.
Long ago (possibly) hunted by locals for its meat, the iguana now has another economic use, being of high importance for the ecotourism industry in this part of the Bahamas.
In 1892 the American ornithologist, taxidermist and all round naturalist Charles Johnson Maynard visited U Cay and found the iguanas "not uncommon" there.
These two he promptly shot (one was wounded but escaped collection), and the following year the secured specimen was made the holotype of a purportedly new species in a paper by the herpetologists and taxonomists Thomas Barbour and Gladwyn Kingsley Noble.
Barbour and Noble state the Cyclura iguanas are "excellent for food" and claim the new species was "beyond doubt extinct", due to being constantly hunted by the poor Negroes who inhabited the poverty-stricken colony.
[11] Among the restricted amount of plant species found growing on its islands are Borrichia arborescens, Bumelia americana, Casasia clusiifolia, Conocarpus erectus, Coccoloba uvifera, Drypetes diversifolia, Eugenia foetida, Guaiacum sanctum, Ipomoea indica, Jacquinia keyensis, Leucothrinax morrisii, Manilkara bahamensis, Pithecellobium keyense, Rhachicallis americana, Solanum bahamense, Suriana maritima, Sesuvium portulacastrum, Sophora tomentosa, Thalassia testudinum and Uniola paniculata.
On Alligator Cay there are 24 species of plant of which the most abundant are Borrichia arborescens, Cyperus sp., Guapira discolor, Pseudophoenix sargentii and Rhachicallis americana.
[11] Outside of the mating season, male rock iguanas have dominance hierarchies rather than strictly defended territories like Cyclura from other islands.
[12] However, a 2000 report demonstrated this theory tested on Alligator Cay, which is free from tourists, and also found a low amount of male-to-male aggression in this species.
[1] On Alligator Cay the population eats mostly Rhachicallis americana and Suriana maritima, the former is more common and is eaten more, but the lizards show a preference for the latter, which is relatively much more uncommon on the island.
On Alligator Cay three plants were not observed to be eaten: Hymenocallis arenicola and Strumpfia maritima, and the mangrove Rhizophora mangle.
They had hypothesized that the gigantic iguanas were eating shearwater carcasses killed by mice and barn owls, but they found no evidence for that hypothesis.
The added nutrients came from the ocean in the form of seabird guano; the largest colony of Audubon's shearwaters (Puffinis iherminieri) are located on Allen's Cay.
Their evidence strongly supports that these iguanas are herbivores and the giants on Allen Cay are so large because their plants contain higher levels of nutrients from seabird guano.
[1] The population on Allen's Cay was at 20–25 for a number of decades according to Iverson, but it was reduced to ten individuals in 2013 indirectly due to bird conservation activities.
[11][13] According to the IUCN the population declined over the next decade due to hurricane damage of the vegetation and emigration to the nearby island of Narrow Water Cay.
The Flat Rock Reef Cay population appeared in the mid-1990s, the IUCN claims it was purposely introduced without authorisation by unknown people.
A number of tour operators and sometimes private yachts moor at either of the islands, bringing a few hundred tourists a day to see the lizards on both Leaf and U Cay.
Tourists may transmit diseases and parasites and sometimes feed the iguanas unnatural food such as foreign fruit, bread, brownies or meat which is believed to contribute to health problems for the lizards such as faecal impaction and high levels of cholesterol.
[13] A century ago, in the early 1900s, the Allen Cays rock iguana was almost wiped out due to being hunted for food by locals (see taxonomy section above).
[1] Allen's Cay was formerly over-run by the common house mouse (Mus musculus), an invasive species, and these were in their turn attracting barn owls (Tyto alba) from neighbouring islands.