More blues needed to survive

The violent killings of seven blue iguanas in May have made people in Cayman and around the world more aware of just how unique and rare these animals are.

iquana eggs

Fred Burton adds water to a container in which the seven iguana eggs are being incubated. Photo: Carol Winker

They exist in Grand Cayman and nowhere else in the world. And they are considered critically endangered because there are so few of them.

How many blue iguanas are there? As of this date — not enough to ensure the survival of the species.

Fred Burton, director of the Blue Iguana Recovery Programme, said the minimum target for a population to sustain itself living in the wild is 1,000. ‘That’s about the size you need to get away from inbreeding problems,’ he explained.

As of June 2008, that target has yet to be met even halfway. BIRP has documented 380 blue iguanas; only 274 of them in the wild.

But if all the eggs being incubated produce healthy hatchlings, Cayman could have almost 500 blue iguanas by September Barring unforeseen disasters and with one important qualification, the target 1,000 could be reached in another five years.

Mr. Burton provided details of the numbers of iguanas in the wild, in the BIRP captive facility and in incubation.

The National Trust for the Cayman Islands established the recovery programme in 1990 after studies showed the blue iguanas had disappeared from over 90 per cent of Grand Cayman and were on the verge of extinction.

Since 2004, 234 iguanas raised in captivity have been released into the Salina Reserve in East End.

The released iguanas were at least two years old and not yet sexually active. Blue iguanas typically start breeding when they are three or four. In the summer of 2006, BIRP volunteers recorded their first sighting of nestings in the Salina. Mr. Burton has not put a number to ‘whatever young ones are running around’.

He also noted that the very first release of iguanas was in the Queen Elizabeth II Botanic Park. This population of free-roamers is running around 40, he said.

The Botanic Park is home to the BIRP captive breeding facility, which has 106 blues: 33 adults and 73 sub-adults.

The killing of five adult males and two adult females was an appalling loss,’ Mr. Burton said, ‘but put in perspective of where we are with the recovery programme I’m glad at least to be able to say, it won’t stop us reaching our long-term goal of saving this species.’

He clarified a statistic published after the incident: the seven animals killed and two injured did represent one-third of the 27 large breeding adults kept in open, walled pens. However, there were younger blues of breeding age that were still in cages.

With the apparent recovery of the two injured males, Archie and Billy, the number of final casualties has been lowered to seven – about 18 per cent of the adults in captivity.

The Blue Iguana Recovery Programme refers to the recovery of the species. Adult iguanas nest inside the captive facility. Staff and volunteers collect the eggs. The hatchlings are then cared for until they are two years old.

At that age, some are released while others are kept for controlled breeding. Accurate and detailed records are kept of how closely the males and females are related. Observers note their personalities and which animals seem compatible.

As of last week, there were 91 fertile blue iguana eggs being cared for in an incubation room.

Everything the iguana needs is in the egg except water. In nature, the egg would absorb water from the ground in which it is buried. Incubated by humans, the egg gets water once per week.

Mr. Burton displayed plastic containers with eggs in them and half-filled with vermiculite – a material that gardeners typically add to soil because of its water-absorbing properties, he explained.

‘We mix water with vermiculite – half and half by weight – and put the eggs in that,’ he said. ‘Then we have to maintain the degree of wetness. Some water evaporates. Some water the eggs take in, so we check them every week.’

Some containers have three or four eggs, some as many as seven. They are kept together as the clutch they were found in and the container lids note their parentage.

The eggs are carefully removed and checked for any imperfection. Fungus, for example, could be removed without damaging the egg, Mr. Burton said.

After water has been added and the eggs replaced, the containers are returned to the incubation room where they are kept at a constant temperature of just under 90 degrees Fahrenheit (32 degrees Centigrade).

Some of the eggs are halfway through the 10-week period they need for the animals to develop before they hatch. Normal peak nesting is in June, Mr. Burton explained, so there may be more eggs on the way.

‘This is going to be the biggest hatching ever,’ he said.

But the successful hatchings may create another problem: space.

Mr. Burton said the blue iguanas need low scrubland as their natural habitat. ‘They need sunlight coming down to the ground – not forest and not wetland.’

He estimated that only 85 acres of the Salina Reserve is suitable: iguanas have not been seen outside that area, he said. The maximum number of blues the area could accommodate is probably 400, Mr. Burton said.

If another protected area can be found, and if there are no disasters, the target 1,000 population in the wild could be reached by 2013.

‘Then the Blue Iguana could come off the critically endangered list and just be endangered,’ Mr. Burton said.

Why blue?

The website of the National Trust for the Cayman Islands explains the Blue Iguana’s most distinctive feature. Iguanas are cold-blooded and need to warm themselves in the sun to become active. Early in the day, when they are cool, adults are dark grey. This colour absorbs heat very efficiently. As the animal warms up, it has to ensure that it does not overheat. To achieve this, the cells responsible for this colouration contract, revealing the distinctive powder blue that is paler and does not absorb heat well.

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