The Blue Iguana Recovery Program of the National Trust for the Cayman Islands recently released 20 iguanas in the Salina Reserve and 29 in the Colliers Wilderness Reserve. Two more adult blues will be released later this year.
Program Director Fred Burton said the releases went off without a hitch, despite the difficult terrain associated with the reserves.
“It all went very smoothly this year,” he said. “We have done so many of these releases now, we have got quite efficient about it.”
He added that the relatively small number of iguanas released this year was a result of the program’s shifting focus on genetic diversity.
“As we get closer to our goal of [approximately] 1,000 in the wild, we are focusing on boosting representation from the least represented family lines, which are that way because we have had least success breeding those in captivity,” he said.
Mr. Burton also said it is getting increasingly difficult for the program to estimate the wild population of blues.
“The way I look at it now, we have in our database 857 known blue iguanas that either we have bred and released or were found in the wild, tagged and let free again,” he said.
However, the program does not know for certain how many iguanas have died or been born. Although the program has evidence of both, Mr. Burton said that unrecorded births and deaths may be taking place in the wild.
“We suspect that unrecorded wild reproduction at least matches unrecorded deaths, so we think the real number in the wild is likely to be at least 857 and quite possibly more,” he said.
The known populations of the Salina Reserve and Colliers Wilderness Reserve, including wild born iguanas that were found and tagged, currently stand at 428 and 308, respectively.
Mr. Burton said that, although wild born iguanas found in the Queen Elizabeth II Botanic Park were tagged and re-released, no new blues were freed in the park this year.
“We have to run the numbers to be sure, but it is beginning to look as though the Queen Elizabeth II Botanic Park blues population may be sustaining itself now, despite the unfortunately high losses to dogs and road kill,” he said.
The newly released iguanas will not be monitored for the next few months.
“We will leave them quietly alone for the most part and let them be wild iguanas,” Mr. Burton said, adding that the population in the Colliers Wilderness Reserve will be surveyed in March to compare with a survey of the Salina Reserve completed in 2012.
“These surveys tell us how close we are getting to the point [where] these populations are sustaining themselves without our help,” he said, noting that the Salina population is still a few years from being self-sustaining.
If the Blue Iguana Recovery Program reaches its target total population of blues in the wild, Mr. Burton said, the breeding and head-start facility may be able to close.
“We will continue to put effort into monitoring the released populations and when we are confident they are supporting themselves, we will be able to release our adult breeders and substantially close the captive breeding and head-starting operation,” he said.
The program’s mission will then focus more on managing the wild blues.
“From there, our efforts will be on protecting the wild population and working on ways to generate sustainable income to the program so that ongoing management of the protected areas and the iguanas can be maintained,” Mr. Burton said.
“This will be necessary because the threats that brought the blue iguanas to brink of extinction are all still here and are never likely to go away,” he said.