The Galapagos land iguana once roamed the islands in impressively large numbers. Back in 1835, Charles Darwin himself once lost his temper with the lizards, complaining that he “could not for some time find a spot free from their burrows” to pitch his tent on Santiago Island. However, populations of land iguanas have unfortunately suffered enormous losses since the 1970’s and in fact, the population on Santiago that so frustrated Darwin has now become completely extinct.
In 1959, the Galapagos land iguana populations were considered to be robust; however, just fifteen years later, in 1975, two populations were completely wiped out in less than six months by packs of feral dogs (one at Cerro Cartago on Isabela Island and the other at Conway Bay on Santa Cruz Island). Furthermore, introduced rat and cat populations were consuming land iguana eggs and young, while introduced goats competed with the iguanas for food.
Other Galapagos animals such as giant tortoises also suffered from attacks by feral dogs; however, the problem was more pressing for the Galapagos land iguana. The natural predators of the land iguana, such as hawks and snakes, do not prey on the lizard after it is about one year old, simply because the iguana is too big. However, feral dogs were able to kill and eat the iguana no matter its size, creating a life-long predator for the lizard. Cats presented an additional threat, as they are able to kill iguanas until they are three or four years old.
This not only complicates the survival and reproductive success of the Galapagos land iguana, but also the repatriation process. Experts could not simply place the lizards back into the wild once they were a year old, as had been done with the giant-tortoise breeding program. Instead, all of the feral dogs present around the populations of land iguanas had to be eliminated before releasing the lizards, significantly complicating the process.
Conservation Efforts for the Galapagos Land Iguana
In the late 1970’s, a breeding and rearing center was established to aid the threatened land iguana populations. As it was not possible to fit all of the young and adult iguanas in the center, about half of the group was released onto the small islet of Venecia, just off Santa Cruz Island. Here, the iguanas were able to live under mostly natural conditions, with the exception of a manmade nesting site, which was built as the islet was not large enough to provide for a natural one. Happily, the program was a great success and, to this day, iguanas continue to breed on Venecia, from where many of the resulting juveniles are repatriated onto Santa Cruz. A fairly large number of individual from this population also roam freely right at Cerro Dragon visitor site, and explorers can see how the eradication program benefited the land iguanas at this site. Now, the iguanas reproduce normally as it happened before the strong impact of introduced animals of the 60s and 70s.
However, the land iguanas on Baltra Island survived mostly thanks to chance. When the Hancock Expedition visited the island in 1932 and 1933, the iguanas they saw (which are known to be the largest in the archipelago) appeared malnourished, apparently due to vegetation loss as a result of introduced goats and probably habitat destruction in some feeding and nesting areas. Thus, to help the iguanas, the members of the expedition moved 70 of them to North Seymour, where no land iguanas lived at that time, but neither did goats. The population on Baltra disappeared around 20 years later, but luckily still inhabited North Seymour. Hundreds of the iguanas have since been repatriated to Baltra, where they appear to be thriving. Visitors can now see iguanas regularly on North Seymour, where just back in the 80s and 90s seeing a couple of them was considered a very lucky event. The more lucky ones sometimes may find one or two right at the airport of Baltra Island.
The National Park has carried out extensive projects to eliminate invasive animals in the islands, such as goats and rats, and while it still performs periodic cat controls, these projects have been extremely successful. Today, all Galapagos land iguana populations appear to be healthy and increasing. At the Charles Darwin Research Station, visitors can see how this program works and a fair number of corrals show how breeding in captivity works.
The Pink Galapagos Land Iguana
The pink Galapagos land iguana is currently the most threatened population of land iguanas, with only about 100 individuals. Although it was first sighted in 1986, the pink iguana was only recently proven to be its own species in the early 2000’s. However, despite its late discovery, further studies have shown that the pink iguana is not new to the islands. Experts believe that it diverged from the other two species of land iguana around 5.7 million years ago and has since evolved to be morphologically, behaviorally and genetically different from the other two species in the Galapagos.
Apparently, the pink iguana population has greatly suffered at the hand of invasive black rats and feral cats, which consume the eggs and young. The small population size and limited distribution (they are only found in a remote area of the highlands up on Wolf Volcano, Isabela Island) further threatens the lizard, making it vulnerable to environmental events such as volcanic eruptions and drought. Further research is required to determine more information on the population’s biology and ecology, its habitat trends, reproductive biology and health status in order to establish an effective conservation program. This area is not a visitor site, and the National Park is not planning on exposing this species and its habitat to tourism.
Galapagos is Reptile Kingdom
Exploring visitor sites that interact with land iguanas is not too difficult, but you need to be on board a Galapagos cruise or take day trips to islands of the National Park that have such wild colonies. Best visitor sites for spotting land iguanas: Urbina Bay (Isabela Island), Cerro Dragon (Santa Cruz Island), and the islands of South Plaza, North Seymour, Santa Fe (this particular one is an island endemic).
Visit our Western & Eastern Itineraries to see the Galapagos land iguana!
Photo Credits: Francisco Dousdebés, Galapagos National Park Service (pink iguanas)