Most Popular Article in Cayman Islands, September 2016
Three unusual hatchling iguanas from Little Cayman have just
been examined by the Cayman Islands Department of Environment and
found to be hybrids. They are apparently the offspring of an
invading Green Iguana female which mated with a native Sister Isles
Genetics work is now being scheduled by Dr. Mark Welch, in his
laboratory at Mississippi State University. This is expected to
confirm the unexpected discovery. The strangely coloured and
patterned hatchlings show intermediate characteristics for features
that normally distinguish the two species. Cross breeding is the
only credible interpretation.
Cross-breeding between Green Iguanas and Rock Iguanas has never
been considered possible, because the genetic difference between
the two was thought to be too profound. Now that it has occurred,
perhaps for the first time, this must be considered a new and
serious risk for Rock Iguanas throughout the West Indies, wherever
the Green Iguanas have invaded.
The first of the hybrid hatchlings was recently caught in the
wild by Mike Vallee, who with fellow volunteer Ed Houlcroft
coordinates "Green Iguana B'Gonna", which is a
programme of the National Trust for the Cayman Islands on Little
Another two hybrid hatchlings were caught soon afterwards by
Jeanette Moss, field assistant Tanja Laaser, and Dr. Mark Welch.
Moss has been in Little Cayman leading the Mississippi State
University research team studying the Sister Isles Rock Iguanas, in
partnership with the Cayman Islands Department of Environment and
the San Diego Zoo Institute for Conservation Research.
The hatchlings are small, like Green Iguana hatchlings, with the
same long striped tails but with different-shaped heads. The body
shows classic rock iguana patterns of dark chevrons and spots.
Under the rock iguana patterns shines a yellow base colour tinged
It cannot be determined at this early age whether the hybrids
will be fertile, or even if they will develop normally. Since their
presence in the Cayman Islands is a serious risk to native Rock
Iguanas, the hatchlings will be transferred to the San Diego Zoo
Institute for Conservation Research, to rear and test for fertility
over the next several years.
In searching for more of these hatchlings, the local volunteers
were joined by the Mississippi research team. No more hybrid
hatchlings have yet been found. It is unknown how many more may
have hatched from the hybrid nest, and dispersed into the
Residents and visitors in Little Cayman are asked to keep an eye
out, and contact Ed Houlcroft or Mike Vallee in person or on
929-5655 or 924-4991 respectively, or at email@example.com
anyone spots a bright yellow-green, striped, and unusually small
iguana hatchling with a long, thin, banded tail.
Green Iguana hatchling (top) and one of the hybrid hatchlings
(below). Photo by DoE.
Sister Isles Rock Iguana hatchling (top) and one of the hybrid
hatchlings (below). Photo by Jeanette Moss / Tanja Laaser
DepartmentofEnvironment – Fred Burton, Manager /
Terrestrial Resources Unit
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