Grand Cayman Blue Iguana – History & Habitat

NATURAL HISTORY

Blue Iguana Captive Breeding Facility

Blue Iguana Captive Breeding Facility

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.

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.

Historical Timeline

  • 1902 – First known instance of Blue Iguanas
  • 1990 -Captive breeding program initiated by the National Trust of the Cayman Islands at captive facility in Queen Elizabeth II Botanic Park on Grand Cayman
  • 1991 – Initial breeding stock found to be hybridized with Cyclura nubila caymanensis; animals sterilized and released in radiotracking study
  • 1992 -Surveys estimate that only 100-200 Blue Iguanas remain in the world
  • 2001 -Blue Iguana Species Recovery Plan formulated during Iguana Specialist Group Meeting on Grand Cayman
  • 2002 -Surveys reveal that the Blue Iguana is functionally extinct in the wild with only 10-25 animals remaining.
  • 2003 -Based on genetic studies, Cyclura lewisi elevated to full species status.
  • 2004 -IRCF organizes first group of international volunteers, dubbed “Team Blue” to construct new cages and refurbish the captive breeding facility.
  • Hurricane Ivan (category 4 storm) devastates Grand Cayman; IRCF assists with rescue and cleanup effort.
  • 2004-2005 – First group of hatchlings released into the Salina Reserve; second Team Blue assists with release and radiotracking.
  • 2005 -IRCF web campaign raises money for 100 new prefabricated hatchling cages. Five-year review of 2001 Species Recovery Plan. IRCF facilitates Dart Foundation grant to complete security fence, and construct a storage shed and food preparation area at the Captive Breeding Facility.

HABITAT

Blue Iguana Habitat  Photo: John Binns

Blue Iguana Habitat Photo: John Binns

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.

A typical example of  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.”  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!

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!
Blue Iguana Habitat.  Photo: John Binns

Blue Iguana Habitat. Photo: John Binns

The Blue Iguana is primarily herbivorous, consuming leaves, flowers, and fruit from at least 45 different plant species in 24 different families. This diet is rarely supplemented with insects, crabs, slugs and fungi.