Allen Cays rock iguana facts for kids
Quick facts for kids Allen Cays rock iguana |
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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: | |
| Subspecies: |
C. c. inornata
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| Trinomial name | |
| Cyclura cychlura inornata (Barbour & Noble, 1916)
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| Synonyms | |
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The Cyclura cychlura inornata, also known as the Allen Cays rock iguana, is a special type of northern Bahamian rock iguana. You can find these amazing lizards on Allen's Cay and other nearby islands in the Bahamas. Sadly, they are currently listed as critically endangered on the IUCN Red List.
Even though they faced tough times in the past, their numbers have been slowly growing. In 1916, people thought they were gone forever. But by 2018, at least 482 adult iguanas were counted on Leaf Cay and U Cay. Hundreds more live on other islands where they have recently moved, sometimes with help from scientists. Many young iguanas are also thriving.
These iguanas are usually large lizards, growing up to 75 centimeters long. Interestingly, some iguanas on Allen's Cay grew twice as big as those on other islands. Scientists believe this happened because Allen's Cay gets a lot of guano (bird droppings), which makes the plants extra nutritious. Sadly, many of these giant iguanas were lost during a conservation effort that went wrong. They were moved to another island and did not survive. Luckily, some iguanas avoided capture and survived on Allen's Cay.
Many people visit Leaf Cay and U Cay to see these iguanas. The lizards have learned to expect food from tourists. They often gather on the beaches, waiting for visitors. Unlike some other Cyclura iguanas, these lizards are quite friendly with each other. They don't usually fight over territory. Long ago, locals might have hunted them for food. Today, these iguanas are very important for ecotourism in the Bahamas. They help bring visitors and support the local economy.
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Discovering the Allen Cays Rock Iguana
In 1892, a naturalist named Charles Johnson Maynard visited U Cay. He noted that iguanas were common there. When he returned in 1915, he found only two. These two were collected for study. In 1916, scientists Thomas Barbour and Gladwyn Kingsley Noble officially described this new species. They named it Cyclura inornata.
At that time, Barbour and Noble believed these iguanas were likely gone due to hunting by local people for food. They mentioned seeing iguana meat for sale in New Providence.
The Allen Cays rock iguana is one of three types of Northern Bahamian rock iguana. The other two are the Andros Island iguana and the Exuma Island iguana. Scientists found that the Allen Cays iguana is very similar to the Exuma Island iguana. This suggests they were once part of a single large population. This was likely about 18,000 years ago, during the last ice age, when the islands were connected.
What Do Allen Cays Iguanas Look Like?
The Allen Cays rock iguana is a large lizard. On Allen's Cay, some can grow to almost 1.5 meters long. However, iguanas on other islands are usually half that size. Their bodies are dark gray to black. Their legs, back crest, and head have yellowish-green or orange scales. As they get older, the yellow colors turn into a bright reddish-orange. This contrasts with their darker striped bodies and black feet.
Like other Cyclura iguanas, males and females look a bit different. Males are larger than females. They also have bigger femoral pores on their thighs. These pores release special chemical signals called pheromones.
Where Do These Iguanas Live?
This iguana subspecies lives only in the northern Exuma Island chain in the Bahamas. Before the 1990s, they lived only on Leaf Cay and U Cay. Later, they started moving to nearby islands like Allen's Cay and Flat Rock Reef Cay. They might have swum or floated to these new places. Sometimes, humans also helped them move.
Small groups of iguanas are now found on tiny surrounding islets. Some were even moved on purpose to Alligator Cay, 30 kilometers south. From there, they seem to have spread to Narrow Water Cay and Warderick Wells Cay. The IUCN reported in 2018 that most of these moves to new islands were helped by people. Scientists have found slight genetic differences between the U and Leaf Cay populations. This also suggests that people have moved iguanas between islands. Leaf Cay seems to be the original source for iguanas on other islands.
Life in the Bahamas
These iguanas live in low, open forests, coastal shrublands, and along beaches. They can be found from sea level up to 10 meters high. The forests in these areas can grow up to seven meters tall. From December to April, the weather is cooler and drier.
Many different plants grow on these islands. Some examples include Borrichia arborescens, Coccoloba uvifera (sea grape), and various palms. Leaf Cay alone has about 48 plant species. Alligator Cay has 24 plant species, including more mangroves. The iguanas need sandy areas at least half a meter deep for nesting.
Native night herons live on these cays. They sometimes eat baby iguanas.
Daily Life and Social Habits
Allen Cays iguanas are active during the day. At night, they hide under palm leaves, in tunnels they dig, or in cracks in limestone rocks. They like to gather in places with many hiding spots. Outside of mating season, male iguanas have a social order. They don't strictly defend territories like other Cyclura iguanas. This might be because tourists regularly feed them on the beach, changing their usual social behavior. However, a study in 2000 on Alligator Cay, where there are no tourists, also found low aggression among males. The study suggested that the small size of the islands might reduce fighting.
What Do Allen Cays Iguanas Eat?
Most iguanas, except the very largest adults, climb plants to find food. They even climb smooth palm trees to eat flower buds. They mainly eat plants, including fruits, leaves, and flowers. They can survive on very small islands with the available plants. On Alligator Cay, they mostly eat Rhachicallis americana and Suriana maritima. They prefer Suriana maritima, even though it's less common.
Scientists have found occasional crab claws, insects, mollusks, and baby birds in their droppings. This shows they sometimes eat meat. They have also been seen eating their own shed skin. Fruits make up more than a quarter of their diet. They eat large fruits like those from Casasia clusiifolia and Manilkara bahamensis. They also enjoy small fruits from sea grapes and palms. Casasia fruits are available all year and are a major food source. Iguanas eat more leaves during the cool, dry season when other foods are scarce.
Scientists Kristen Richardson, John Iverson, and Carolyn Kurle studied the iguanas' diets. Their 2019 study looked at special elements in the iguanas' bodies. They wanted to understand why iguanas on Allen's Cay were twice as long and six times heavier than those on nearby islands. These populations were only one generation apart and separated by a 300-meter channel. The scientists thought the giant iguanas might be eating dead birds. But they found no proof of this.
Instead, they discovered that the giant iguanas ate plants with more nutrients. These extra nutrients came from the ocean, carried by seabird droppings (guano). Allen's Cay has the largest colony of Sargasso shearwaters, a type of seabird. Other islands don't have many seabirds, so their plants lack these extra nutrients. This study strongly suggests that these iguanas are plant-eaters. The giants on Allen's Cay are so big because their plants are richer in nutrients from seabird guano.
Tourists often feed the iguanas human food on Leaf Cay and U Cay. The iguanas have learned to expect this and gather in large groups, waiting for visitors.
Reproduction and Life Cycle
Mating season for these iguanas is in May. Females usually lay their eggs in sandy nests from mid-June to mid-July. They travel to suitable sandy areas to build their nests. Allen's Cay has rocky beaches with no sand, so iguanas have not bred there. However, Alligator Cay and Flat Rock Reef Cay have good nesting spots.
Not all females lay eggs every year. Only about one in three females nests in a given year. However, the largest females usually nest annually. They lay between one and ten eggs. Bigger females lay more eggs. The eggs hatch successfully about 79% of the time. This happens in late September and early October, after about 80-85 days of incubation. The nests stay at a temperature of about 31 degrees Celsius.
Protecting These Special Iguanas
Why Are They Endangered?
The IUCN first listed these iguanas as endangered in 1996 and 2000. In 2018, using stricter rules, they changed the status to critically endangered. This means they are at a very high risk of disappearing.
In the early 1900s, almost all Allen Cays rock iguanas were gone. But by 1970, their population grew to about 150 on the two islands where they bred. By 1982, this number increased to over 200. In the early 1980s, the population grew by about 20% each year. By the end of the century, they had reached the maximum number their original islands could support. In 2000, it was thought there were fewer than 1,000 iguanas globally, and their numbers seemed to be falling. However, they were actually increasing. In 2018, scientists estimated there were 482 to 632 mature adult iguanas. This included 482 adults on U and Leaf Cay in 2016. This number does not count over 150 adult iguanas on islands where they cannot breed.
The population on Allen's Cay was stable for decades. But in 2013, it dropped to ten iguanas. This was partly due to efforts to protect birds. In the 1990s, some iguanas were moved to nearby islands. For example, eight young iguanas were moved to Alligator Cay between 1988 and 1990. Ten years later, at least seven of them had survived. By 1999, their numbers had grown to between 75 and 90. Scientists believed there were many more young iguanas, and the island could support even more. The IUCN reported that this population later decreased due to hurricane damage and iguanas moving to Narrow Water Cay. In 2013, 28 iguanas were seen on Alligator Cay and 38 on Narrow Water Cay. Some iguanas also seemed to have moved to Warderick Wells Cay.
The Flat Rock Reef Cay population appeared in the mid-1990s. The IUCN believes unknown people introduced them without permission. This population quickly grew to about 200 by 2012. However, the IUCN warned in 2018 that the island might not be able to support so many iguanas.
Main Dangers to the Iguanas
The biggest danger to these iguanas, according to the IUCN in 2018, is ecotourism and tourists feeding them. Many tour boats and private yachts visit Leaf and U Cay. Hundreds of tourists come each day to see the lizards. Tourists might accidentally spread diseases or parasites to the iguanas. They also sometimes feed the iguanas unhealthy foods like foreign fruits, bread, or even meat. This can cause digestive problems and high cholesterol for the lizards.
Even though dogs and cats are not allowed, some tourists still bring their pets. Just one loose dog could wipe out an entire iguana population. Also, the IUCN suggests that some tour operators might have moved larger iguanas to other islands. This could be to prevent them from scaring tourists. Scientists found a tagged iguana eight kilometers from where it was tagged. They also noticed that large iguanas seem to be becoming rarer. These iguanas are the main reason tourists visit this part of the Bahamas.
A century ago, in the early 1900s, locals hunted the Allen Cays rock iguana for food. This almost made them disappear. As of 2003, there were still reports of iguanas being hunted for food and captured for the pet trade. The IUCN repeated this concern in 2018, though there is no recent proof of this happening.
Helping the Allen Cays Iguana
All Bahamian rock iguanas, including this species, are protected by the Wild Animals Protection Act of 1968 in the Bahamas. They are also listed under CITES Appendix I, which controls international trade of endangered species.
Allen's Cay once had many common house mice, which are an invasive species. These mice attracted American barn owls from nearby islands. In May 2012, Island Conservation and the Bahamas National Trust worked together. They removed the invasive mice from Allen's Cay. This helped protect the Sargasso shearwater birds and native species like the Allen Cays rock iguana.
Scientists worried that the iguanas might eat the mouse poison. So, eighteen iguanas were moved to Flat Rock Reef Cay. This island already had a small iguana population. Sadly, sixteen of these moved iguanas did not survive by 2013. It is now believed this happened because the plants on Flat Rock Reef Cay lacked the extra nutrients found on Allen's Cay. After this, at least eight iguanas survived on Allen's Cay. Including two from Flat Rock Reef Cay, there are now thought to be ten iguanas left on Allen's Cay. In 2012, a project began to fill small sinkholes on Allen's Cay with sand. This aimed to create suitable breeding areas for the iguanas.
The population on Alligator Cay was started as part of a conservation program. This program involved moving animals to new areas. It was considered very successful in 2001. Alligator Cay and its surrounding islands are now part of the national Exuma Cays Land and Sea Park.
Currently, there are no special breeding programs for this iguana subspecies in zoos or other facilities.
