A Blue Iguana has simple needs for survival and a good life.
- Warmth: access to enough sunshine to maintain a daytime core body temperature at 100 degrees F. That means low, open vegetation – closed canopy forest is too shaded.
- Food: diverse native vegetation to supply food year round. No problem, so long as the natural vegetation is still there.
- Water: small amounts of drinkable water, especially during the dry season. Even a little dew helps.
- Soil: at least a foot depth of soil, exposed to the sun, which is moist during the summer but not flooded – to lay eggs in.
- Shelter: rock holes, to sleep in at night – or soil to make burrows in.
- Safety: freedom from mammalian predators (rats, cats, dogs) which have no natural place in the Caymanian ecosystem.
- Company: other Blue Iguanas, to breed with, to compete with, just to be Blue Iguanas with!
Before people arrived, all those needs were available over large parts of Grand Cayman. Nowadays the options are perilously few.Land like this once supported iguanas. It was cleared and burned to make it more attractive to potential buyers.
All over Grand Cayman, the process of deforestation of native forests, mangroves and shrublands is accelerating, driven by human economic forces. Native plants and animals are helpless against the onslaught.
The National Trust for the Cayman Islands has worked tirelessly over the last decade to set up a system of protected areas, acquiring high priority conservation land by purchases and through donations from individuals and the local government. Two thousand acres of dry forests and mangrove wetlands are now protected in this way, distributed between the three Cayman Islands.
Unfortunately, conservation priorities and economic reality have so far worked against protection of Blue Iguana habitat. Most of Cayman’s unique biodiversity resides in ancient dry forest areas, while the Blue Iguanas are now restricted to degraded farmland and the harsh dry shrubland at the extreme eastern end of Grand Cayman.
The Durrell Wildlife Conservation Trust’s Quentin Bloxam here surveys a typical example of that shrubland, growing on savage dolostone karst rock which poses a formidable barrier to explorers. It provides most of the iguanas’ needs, but soil for nesting is restricted to local depressions which invariably have been farmed at some stage over the past 200 years.
Abandoned farmland in the area has been colonized by non-native pasture grasses, and also supports a dense growth of the highly toxic shrub Comocladia dentata, known locally as “Maiden Plum.” A typical site is shown on the left. Iguanas are deterred from occupying these sites by the pasture grasses, which shade the soil surface and form root mats over potential nest sites. The Maiden Plum deters humans!
Analysis of the very scarce sightings of wild Blue Iguanas over the last 10 years, suggests there may be a core area within this mosaic of shrubland and abandoned agriculture, which may support the majority of the remnant population. Despite the inaccessible terrain, a new survey to define this area, guided by satellite imagery and aerial photography, commenced in December 2001.
Once the true distribution of the wild population has been mapped as accurately as possible, the difficult issue of how to protect their last home must be addressed. It will require a combination of public support, political commitment, and substantial sums of money.
But in truth, no other option can secure a long term future for Blue Iguanas in the wild. With their home protected, the nesting areas restored, and their numbers boosted, a thousand-strong population living natural lives in their own nature reserve, is the vision we are working towards.