Allen Cays rock iguana facts for kids
Quick facts for kids Cyclura cychlura inornata |
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| Cyclura cychlura inornata | |
| Conservation status | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Iguania |
| Family: | Iguanidae |
| Genus: | Cyclura |
| Species: | |
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C. c. inornata
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| Trinomial name | |
| Cyclura cychlura inornata (Barbour & Noble, 1916)
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The Allen Cays rock iguana (Cyclura cychlura inornata) is a special type of northern Bahamian rock iguana. You can find it on Allen's Cay and other nearby islands in the Bahamas. This iguana is currently listed as critically endangered on the IUCN Red List, meaning it's at a very high risk of disappearing.
Even though it was once thought to be extinct in 1916, its population has been growing! By 2018, there were at least 482 adult iguanas counted on two main islands, Leaf Cay and U Cay. Hundreds more have spread to at least five other islands nearby, sometimes with help from people.
These iguanas are quite large, usually about 75 centimeters (about 2.5 feet) long. But on Allen's Cay, some iguanas grew to be twice as big! Scientists think this happened because of the large amount of guano (bird droppings) on that island, which makes the plants they eat extra nutritious. People often visit these iguanas, and the lizards have learned to expect food from tourists. Unlike other Cyclura iguanas, these ones are very friendly with each other and don't fight over territory. They are also very important for ecotourism in the Bahamas.
Contents
About the Allen Cays Rock Iguana
What is its scientific name?
In 1916, two scientists, Thomas Barbour and Gladwyn Kingsley Noble, first described this iguana. They named it Cyclura inornata. They believed it was already extinct because people used to hunt it for food.
The Allen Cays rock iguana is one of three subspecies of the Northern Bahamian rock iguana. The other two are the Andros Island iguana and the Exuma Island iguana. Scientists believe all these iguanas were once part of one large population about 18,000 years ago, when the islands were connected during the last ice age.
What does it look like?
The Allen Cays rock iguana is a large lizard. The ones on Allen's Cay can grow up to 1.5 meters (about 5 feet) long! Normally, these iguanas are about half that size. Their bodies are dark gray to black. They have yellowish-green or orange scales on their legs, head, and the crest along their back. As they get older, the yellow colors turn into a bright reddish-orange.
Like many lizards, male and female Allen Cays rock iguanas look a bit different. This is called sexual dimorphism. Males are usually larger than females. They also have bigger femoral pores on their thighs, which are special glands that release pheromones (chemical signals).
Where does it live?
This iguana lives only in the northern Exuma Island chain in the Bahamas. For a long time, it was only found on Leaf Cay and U Cay. But since the 1990s, it has started to live on nearby islands like Allen's Cay and Flat Rock Reef Cay. They might have swum or floated to these new islands, or sometimes people helped them move. Small groups of iguanas are also found on tiny islets around these main islands.
Some iguanas were even moved on purpose to Alligator Cay, about 30 kilometers (18 miles) south. From there, they seem to have spread to other islands like Narrow Water Cay. The IUCN says that most of the new populations on other islands were started by humans.
What is its habitat like?
These iguanas live in low, open forests, along beaches, and in coastal shrubland. They can be found from sea level up to 10 meters (33 feet) high. The forests where they live can grow up to seven meters (23 feet) tall. The islands have a cooler, dry season from December to April.
The iguanas need sandy areas at least half a meter (1.6 feet) deep to dig their nests. The cays also have native night herons, which sometimes eat baby iguanas.
How do they behave?
Allen Cays rock iguanas are diurnal, meaning they are active during the day. At night, they hide under the leaves of thatch palms, in tunnels they dig, or in holes and cracks in limestone rocks. They like to gather in places with lots of these hiding spots.
Outside of mating season, male iguanas usually have a social order instead of strictly defending their own areas, which is different from other Cyclura iguanas. This might be because tourists regularly feed them on the beach, which changes their normal social behavior. However, a study in 2000 found that even on islands without tourists, these iguanas showed less aggression between males. This suggests that the small size of their islands might also play a role.
What do they eat?
Most iguanas, except the very largest adults, climb into plants to find food. They even climb up smooth palm trees to eat flower buds. They mainly eat plants, including fruits, leaves, and flowers from many different plants. They can survive on very small islands by eating the plants available there.
Scientists have also found small amounts of crab claws, insects, mollusks, and young birds in their droppings, so they sometimes eat meat. They have even been seen eating their own shed skin!
A study in 2019 looked at why iguanas on Allen's Cay were so much bigger. They found that these giant iguanas were eating plants with more nutrients. These extra nutrients came from the ocean in the form of seabird guano (droppings). Allen's Cay has a very large colony of Audubon's shearwaters, a type of seabird. The other islands don't have as many seabirds, so their plants don't get as many extra nutrients. This study strongly suggests that the iguanas are so big because the plants they eat are richer in nutrients from the seabird guano.
Tourists often feed the iguanas human food on Leaf Cay and U Cay. The iguanas have learned to expect this and will gather in large groups on the beach, waiting for visitors.
How do they mate?
Mating season for these iguanas is in May. Females usually lay their eggs in mid-June to mid-July. They dig nests in sandy areas. Females will travel to suitable nesting spots. On Allen's Cay, there isn't enough sand for nesting, so the iguanas there have never bred. The subspecies used to breed only on U and Leaf Cay, but now they also have good breeding sites on Alligator Cay and Flat Rock Reef Cay.
Not all females nest every year; usually, only one out of three does. However, the largest females lay eggs every year. They lay between one and ten eggs, with bigger females laying more. The eggs hatch in late September or early October, after about 80 to 85 days of incubation, if the nest temperature is around 31 degrees Celsius (88 degrees Fahrenheit). About 79% of the eggs successfully hatch.
Protecting the Allen Cays Rock Iguana
What is its conservation status?
The IUCN first listed this iguana as endangered in 1996 and 2000. But in 2018, using stricter rules for counting, they decided the population was actually critically endangered.
In the early 1900s, the population was almost wiped out. But by 1970, it had grown to about 150 iguanas on the two islands where it bred. By 1982, this number increased to over 200. The population grew quickly, by about 20% each year in the early 1980s. By the end of the century, it had reached the maximum number its original islands could support. In 2018, the total adult population was estimated to be between 482 and 632 individuals. This number doesn't even include over 150 adult iguanas found on islands where they can't breed.
What are the threats?
The biggest threat to these iguanas, according to the IUCN in 2018, is ecotourism and tourists feeding them. Many tour boats and private yachts visit the islands, bringing hundreds of tourists daily to see the iguanas on Leaf and U Cay. Tourists might accidentally spread diseases or parasites to the iguanas. They also sometimes feed the iguanas unhealthy foods like foreign fruits, bread, brownies, or meat. This can cause health problems for the iguanas, such as constipation and high cholesterol.
Even though dogs and cats are not allowed on the islands, some tourists still bring their pets. Just one loose dog could wipe out an entire iguana population. The IUCN also suspects that some tour operators might have moved very large iguanas to other islands so they wouldn't scare tourists. This is because they found a tagged iguana far from where it was tagged, and large iguanas seem to be less common in the population now. Despite these issues, the iguanas are the main reason tourists visit this part of the Bahamas.
A century ago, in the early 1900s, people hunted the Allen Cays rock iguana for food, which almost made it disappear. As of 2003, there were still reports of them being hunted for food and captured to be sold as pets. The IUCN repeated this concern in 2018, though there isn't much recent proof of this happening.
What is being done to help?
Like all Bahamian rock iguanas, this species is protected in the Bahamas by the Wild Animals Protection Act of 1968. It is also listed under Appendix I of the CITES convention, which controls international trade of endangered species.
Allen's Cay used to have many common house mice, which are an invasive species. These mice were attracting barn owls from nearby islands. In May 2012, Island Conservation and the Bahamas National Trust worked together to remove the mice from Allen's Cay. This was done to protect the Audubon's shearwater birds and also native species like the Allen Cays rock iguana.
Because scientists worried the iguanas might eat the rodenticide (mouse poison), eighteen iguanas were moved to Flat Rock Reef Cay. Sadly, sixteen of them starved to death by 2013. It's now believed this happened because the plants on Flat Rock Reef Cay didn't have the same extra nutrients as the plants on Allen's Cay. After this, at least eight iguanas survived on Allen's Cay, and with two from Flat Rock Reef Cay, there are now thought to be ten iguanas left on the island. In 2012, a project began to fill small sinkholes on Allen's Cay with sand to create suitable breeding areas for the iguanas.
The population on Alligator Cay was started as part of a conservation program to move iguanas to new areas. This program was considered very successful in 2001. Alligator Cay and the islands around it are now part of the national Exuma Cays Land and Sea Park.
Currently, there are no special breeding programs in zoos for this subspecies.
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Cyclura cychlura inornata
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