2007 Program Update
The Jamaican Iguana was once feared extinct and a live individual was not seen for nearly half a century. Rediscovered in 1990, this species is now making a recovery thanks to the efforts of a dedicated group of individuals and organizations. The species is threatened primarily due to the introduced Indian Mongoose, which consume a very high percentage of all recently hatched wild iguanas. To overcome this high juvenile mortality and boost the adult ranks, hatchings are collected as soon as they emerge from the nest and transported – 266 to date – to the safety of the Hope Zoo for headstarting. When they are large enough to survive a mongoose attack, they are released to the wild. In recent years, headstarted female iguanas have returned to their natal hatching site to lay eggs, conclusive evidence that they are integrating with the remaining wild population. Since the releases, a number of the iguanas have been seen over feeding in Tabebuia trees, the same species that other wild iguanas have been observed feeding on over the past two weeks. It is both remarkable and reassuring that headstarted iguanas that have spent their entire life in captivity can transition to the wild so smoothly and display similar behaviors as their wild counterparts.
Other newsworthy bits of information continue to roll in from Rick van Veen and the field team that include:
- Ecology, movements, and home range: 40 adult iguanas (10 wild) were studied between late May and October, 2006, resulting in >500 recorded GPS positions. Also recorded >1500 way points for various other iguana sign (e.g., scats, feeding marks, active retreats [rockholes], scratch marks, tail drags, nesting attempts, major feeding trees, worn basking sites, and active trails). The primary goal of this exercise was to determine the non-nesting season home ranges of the females using the two main nesting areas. Turns out they were not coming from long distances. For example, the greatest distance (from nesting area to home range) was less than 300 meters. Several home ranges include rock ledges that appear to have been used for hundreds (?) of years – that is, deeply worn grooves in areas of the rock that they slide down using their hind claws as anchors. Most, if not all of the older iguanas inhabit the steepest slopes in the most rugged terrain (dog proof perhaps?). Four new wild iguanas were captured and implanted with PIT tags, two of which were nesting females (stained red from digging), though the location of the nests could not be confirmed.
- 2006 nesting season: In addition to the upper and lower communal nest sites a number of other nesting areas have been found since 2004 and include a new area found quite recently (Feb 2007). There appears to be a number of different types and qualities of nest sites, which are identified by quality of drainage at the sites. For example the primary communal sites of the upper and lower nest sites are in open red soils, which are well drained. The other sites are in rock holes where quality of drainage varies greatly. At the two primary open soil sites there were 14 confirmed nests in 2006, 13 from the upper and lower communal nest sites and one at the field station.
- Hatchling survivorship: At least three hatchlings are known to have survived since 2004 within the predator trapped area. One of these was a radio-tracked animal, the others were from wild (non-pit tagged) animals whose nest locations remain unconfirmed.