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History, status and future for ROCK IGUANA (Cyclura nubila caymanensis) ON CAYMAN BRAC

Iguana on Cayman Brac

Iguana on Cayman Brac


DEFINITION (Speciation)

The rock iguana (Cyclura nubila Caymanensis) is unique to the “sister islands” Cayman Brac and Little Cayman, which are the two smaller islands of the three Cayman Islands. It is a subspecies of the Cuban Rock Iguana. (Source: website of the National Trust for the Cayman Islands).

ANCIENT ORIGIN

The common, ancient ancestors of our sister islands Rock Iguana doubtless arrived at about the same time, and of the same stock, as the ancestors of the Grand Cayman Blue Iguana (Cyclura lewisi): “The founding Rock Iguana stock, probably from ancient Cuba, drifted ashore accidentally some two to three million years ago — when falling sea levels had just exposed the island after an unimaginably long time under the ocean.” (FJ Burton, The Little Blue Book, 2010.) National Trust Information Sheet #18 (1996) calls The Blue Iguana Cyclura nubila lewisi, and says it is a subspecies of the Cuban Rock Iguana and closely related to the rock iguana found on Cayman Brac and Little Cayman. We know that the “Blue” will breed with the Sister Islands Rock Iguana and produce viable young, fully capable of breeding in their turn. (Little Blue Book, pp. 50 to 54.)

[NB: Back to 1996: Information sheet #18 notes an integrated conservation program introduced on Grand Cayman in 1990, including field research, captive breeding, public education, habitat protection and reintroduction.]

National Trust Information Sheet # 62 (also 1996) covers the sister islands’ Rock Iguana, although the sheet is entitled Little Cayman Rock Iguana. This useful sheet will be used further in the present brief status report.

An artist has depicted a thought-provoking painting of the forest floor as it might have appeared two million years ago, including the Rock Iguana. It could depict any of the three Cayman Islands. (Islands from the Sea, 2006, author M.A. Roed, geologist and painter, p. 10.)

HUMAN HISTORY

Some of the earliest maps of the Cayman Islands (1600s) show the caiman and the turtle, but unfortunately not the iguana, although it was widespread. Quoting NT Info Sheet #62 again, the earliest settlers to Cayman Brac (almost 200 years ago) brought their dogs, and “The dogs soon learned that killing iguanas was an exciting way to get an extra meal.” Continuing, “A once abundant iguana population has now been reduced to a few tens of survivors. Now another domestic animal threatens to be the death knell for the iguana population on Cayman Brac: feral cats are now found in huge numbers, and they eagerly pursue juvenile iguanas.” (The same article estimates Little Cayman’s iguana population at 2500. It goes on to warn of increasing threats from dogs, cats and cars. Sadly, this warning has proven to be valid.)

Reviewing this account from a Cayman Brac perspective, one can only agree with its pessimism. There are more enemies than the ones listed! Direct human predation occurred, partly because farmers did not like iguanas digging around their tubers and other produce. (The iguanas need soft soil or sand to dig their nesting cavities, and they eat vegetables and fruit.) Further, a more recent competitor is the introduced green iguana. Apparently it is here on Cayman Brac, and we all must assist our conservation officers to eradicate it, now that it is legal to do so. (We should think of this invader in the same way we think of the invasive Lionfish. It was introduced accidentally and now must be extirpated since it destroys native species and whole eco-systems.)

The oral history of the iguana on Cayman Brac has not been written. It is still easy to obtain, say from the 1950s to now, by interviewing those who have been around since that time. For example, we have reliable word of sizable numbers of iguanas at the southern end of Ashton Reid Drive in the sixties and seventies– plentiful enough that some were shot.

PRESENT AND FUTURE

We wish to demur from the assessment of Info Sheet #62, which states “The tiny iguana population surviving on Cayman Brac is too small to be regarded as viable in the long term.” But we fully agree to the next statement: “… a concerted effort to reduce the thousands of feral cats, many living in hunger and misery in the woodlands, must first be undertaken.” (In this regard we must give credit to our local Humane Society and its spaying and neutering policy.) Further, land must be reserved and protected as habitat. This is underway, albeit very slowly.

Based on the observation of Brac district committee members (about 35 in number) we estimate the present number of iguanas on the Brac to be about 100. We have direct evidence of about 50 (local naturalist T.J. Sevik agrees) and the factor of two is conservative because our terrain should hide many iguanas. So it seems the “few tens of survivors” in 1996 totals about ten tens of survivors, in 2010, against all obstacles.

We have identified critical habitats to be protected by acquisition. Further, we are prepared to draft a voluntary protocol for land-owners, whereby they would sign up to certain conditions to share their properties with our native iguanas, and to protect our native creatures and their habitat from predation and destruction.

We have evidence that iguanas lived IN ALL PARTS of Cayman Brac, in historic times. Today the biggest numbers we know of live in West End, the south side of Stake Bay Forest, the lowland south of that forest, and BOTH bluff edges further east, to and beyond Ashton Reid Drive. We have evidence that along the bluff edge, individual iguanas claim both the bluff top and the land below, and “commute” at will. We live in hope that there are other populations living, possibly thriving, in the wildest parts of our island where there are no paths. (Paths attract opportunistic dogs, cats, chickens and rats and we prefer to limit roads and footpaths on the island. Within our protected areas such as The Splits we aim for rude, single-file tracks, if any.)

Of the 44 properties we have recommended for protection, 13 are KNOWN to afford suitable habitat for iguana families. We hope the same is true of several more of our nominee properties, in spite of our ignorance. Unfortunately, no properties known to be inhabited by iguanas are presently reserved for them by the Trust, or by any other agency, on Cayman Brac.

Our vigorous local committee knows that our natural environment, subject to the most severe downgrading of the three islands, would suffer sadly if we lost this magnificent creature after its 2 million year “run” on our island. All of us living here, present and future, would be the losers.

jwp

April 2018
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