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Wildlife: Blue Iguanas


Blue IguanaCyclura nubile lewisi;  (Grand Cayman) 

The Blue Iguana "the most endangered iguana in the world" 
Photo by: David Blumenthal
Coming out of egg...
  Size: Males up to 515 mm SVL*; females up to 410 mm SVL. These are rock iguanas and the habitat is open rocky sunlit areas in dry forests or near the shore as females must excavate cavities in the sand or soft soil for laying eggs. They lay about 10 to 15  soft-shelled eggs, in June and July. – Smaller, younger females lay fewer – sometimes only 3 or 4. The young sometimes climb into trees, although adults are never found there.  Diet includes plants, fruits and flowers, but they have recently been observed eating snails, slugs and caterpillars. They don’t hunt per se, but are opportunistic so only catch very slow-moving creatures. Colour is tan to gray with a bluish cast that is more pronounced during the breeding season, especially in males. Individuals vary considerably in the amount of blue colouring and this can change according to time of year, health and shedding. They are particularly large and bulky with a dorsal crest with short spines from the neck to the end of the tail. Very young iguanas do not have the blue colouring and show light and dark bars that extend along the back. Fossils indicate that these iguanas were very common before European colonization, and that they were once larger. These native iguanas evolved in the Cayman Islands with no major predators and have few defences against imported rats, cats and dogs. A recent field census shows that the current wild population has been drastically reduced. Visit www.blueiguana.ky link  or  www.cyclura.com link or www.ircf.org link for more on the Blue Iguanas and their fight against extinction.  A documentary film is being produced by the National Trust Blue Iguana Recovery Programme.
* Key:
SVL Snout to Vent Length

Total Length (including tail)




Blue Iguana
Drawing by Penny Clifford


Green Iguana
Drawing by Penny Clifford


Very often, people cannot tell the difference between the native Blue Iguanas and the introduced and now vastly more common Green Iguanas.

Cayman Islands’ endemic native Blue Iguanas are extremely rare and survive as a viable population here only due to the efforts of the National Trust which established a captive breeding program for them ten years ago and continues to maintain an active, ongoing and multi-faceted programme thanks to the heroic efforts of Mr. Fred Burton and a host of local and international volunteers and sponsors.

Green Iguanas are native to Central America and were brought to the Cayman Islands as pets. In their original homes in Central America, they were accustomed to being surrounded by predators like jaguars, so they are fast, agile and able to climb trees to escape. Our native Blue Iguanas have always lived in relative peace and tranquillity on Grand Cayman where there were no dangerous animals.

Because the Green Iguana is bred to escape predators, it has can escape the attacks of cats and dogs and has therefore multiplied freely in the wild, laying clutches of up to 30 eggs at a time. It is estimated that there are now many thousands of Green Iguanas living on Grand Cayman. Though, at first, the Green Iguanas were found mainly in the West Bay area, they are now being spotted further and further east and there is nothing to stop them from moving to the Eastern districts where they may become a problem for farmers.

Blue and Green Iguanas cannot interbreed. The major threat to our Blue Iguanas is NOT the Green Iguana, but the presence of loose cats and dogs in the ecosystem, preying upon both young and adult Blue Iguanas. High speed traffic is also a problem, now beginning to affect the subspecies living on Cayman Brac and Little Cayman.

Green Iguanas can be a nuisance to homeowners. They eat flowers and garden plants and have a very unfortunate habit of defecating in swimming pools. Blue Iguanas can be seen in the Botanic Park, but are practically extinct in the wild, surviving on only one small area of native cliff and forest near East End.

These drawings show the main differences. If you remember that Blue Iguanas do not have stripes on their tails and do not have spines under their chins, you will be able to identify any iguanas you may see.

To volunteer for the Blue Iguana Project, visit the National Trust. For more on Blue Iguanas visit www.blueiguana.ky To see photographs identifying Blue and Green Iguanas at all stages of life, visit www.blueiguana.ky/bluevsgreen 

Blue Christmas
  Twas the night before Christmas
and all through the Salina, not a creature was stirring, not a single Cyclura.
The stockings were piled by the boots in a heap, in the hopes that some of us might get some sleep!
The trackers were collapsing one by one into beds, while visions of maiden plum danced in their heads.
And iguanas in cages and iguanas in parks, had all settled down, just before dark.
When out on the lawn, there arose such a clatter, I sprang from my bed to see what was the matter.
Away to the window I sleepily did go, for dozens of roosters had started to crow.
When first rays of light shone onto the floor, I knew it was time to head for the door.
When what to my half open eyes should appear, but a tall sleepy Fred holding coffee and gear.
With a long curvy drive going out to the park, the post-Ivan Cayman looked roofless and stark.
With a sharp jagged pathway and a long tedious walk, I knew in a moment it must be cliff rock.
Then gradually out of their retreats they came, and we quietly followed and listed by name.
Came Wymp and Yerp, and Burp and Grape,
Then Gypsie and Egypt and Yarrow and Wop, came Rambo and Wribbit and Gewpy and Gop. Out to the rock, to the top of the retreat, the signal receiver went beep beep beep beep.
Through trees that before the wild hurricane stood, we followed iguanas through cliff rock and woods.
So down the trail to find lizards I walked, to retreat 49 twas Oppie I stalked.
As I punched in the code and was turning around, down fell Oppie from a tree to the ground.
She was ridged with spines from head to tail, and patches of skin were turning quite pale.
A piercing with beads orange pale blue and yellow, this young female lizard was surprisingly mellow.
Her tail ringed with spikelets her toes long and slender, at this age it's too difficult to tell them by gender.
Her head was so turquoise it looked like the sea, from her look I could tell she was tempted to flee.
Her belly was plump, and her eyes so dark red, that they looked like squashed berries in the sides of her head.
She blended into the rock as a measure of stealth, and I laughed when I saw her in spite of myself.
A wink of her eye and a twist of her head, soon gave me to know I had nothing to dread.
She spoke not a word but went on with her eating, and I decided to type you this holiday greeting.
And here once again as the bugs start to bite,
Merry Christmas to all, and to all a good night!
  Written by Sarah Doty, International Reptile Conservation Foundation while on Grand Cayman assisting in the release of Blue Iguanas for the Blue Iguana Recovery Project.
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