Land Iguanas Are Territorial Animals

The males defend specific areas, which usually inlude more than one female. Male Iguanas can be highly aggressive towards each other. Territorial displays involve rapid nodding of the head and, sometimes, biting and tail-thrashing battles.

Land iguanas reach maturity between eight and fifteen years of age, depending on their size. They congregate and mate during specific periods, which vary from island to island. The females then migrate to suitable areas to nest. After digging a burrow about half a meter deep the female lays two to twenty-five eggs in the nest. She then defends the burrow for some time to prevent other females from nesting in the same spot.

The young iguanas hatch three to four months later and then take about a week to dig their way out of the nest. These tiny, speckled iguanas can easily fit in the palm of a hand. If they survive the difficult first years of life, when food is often scarce and native predators such as hawks and owls are a danger, land iguanas can live for more than 60 years.

Land Iguanas Are Well Adapted

Distanlty related to the green iguana of South America continent, Galapagos land iguanas can be over a meter long, with males weighing up to 13 kilograms. Their rough, wrinkled skin is yellowish with scattered pacthes of black, brown and rust. Two species occur in Galapagos - Conolophus subcristatus is native to six islands, while Conolophus pallidus is native only to Sante Fe.

Land iguanas live in the drier areas of islands and in the morning are found sprawled beneath the hot equatorial sun. During the midday heat, however, they seek the protective shade of catcus, rocks, trees or other vegetation. To conserve their body heat at night, they sleep in burrows that they dig in the ground.

Land iguanas are very flexible in their diet but generally depend on low-growing plants and shrubs, as well as the fallen fruits and pads of catcus trees. Although they often scrape the spines off catus pads with their  claws, it is not uncommon for an iguana to bite into a catus pad, spines and all! These succulent plants provide them with most of the moisture they need during long dry periods.

Populations Were Drastically Reduced

When Charles Darwin visited Galapagos in 1835, he wrote about the abundance of the land iguanas: "I cannot give a more forcible proof of their numbers, than by stating that when we were left at Santiago Island, we could not find a spot free from their burrows on which to picth our single tent."

However, when whalers and settlers started visiting Galapagos in the early 1800's, they brought with them goats, pigs, dogs, cats and other domestic animals. Over time, many of these animals escaped or were abandoned, with drastic results. Cats hunt the young iguanas and dogs kill adults. Goats wipe out entire areas of vegetation that the iguanas depend on for food. Today, the abundant iguanas that Darwin wrote about on Santiago Island are extinct. On some other islands, they are nearly gone.

Rescue Operations Are Successful

In 1976, wild dogs wiped out a colony of almost 500 land iguanas at Conway Bay on Santa Cruz. Together, the Charles Darwin Research Station and the Galapagos National Park Service launched an emergency rescue operation for the 60 or so survivors. Shortly thereafter, another large-scale attack occured at Cartago Bay, Isabela, and thirty more iguanas were rescued.

These rescue operations marked the beginning of a captive breeding and rearing program for land iguanas at the Station and Park headquarters on Santa Cruz. There, the eggs from endangered populations of iguanas are incubated. The young are raised until large enough to be safely returned to their island of origin. In the 1980's, adult iguanas that had been moved from Baltra to North Seymour in the 1930's were added to the breeding stock. In 1991, captive-bred iguanas were reatriated to the island of Baltra, where they had been extinct for more than 50 years. Since 1980, over 700 young iguanas have been released back into the wild.

The captive breeding program is reinforced by an on-going campaign for the eradication and control of introduced animals throughout the islands. The populations of wild dogs were eliminated from Cartago and Conway Bays, and goats were removed from several small islands, while pigs and wild cats are now controlled on others. The progam has been such a success at Cartago Bay that all of the adult iguanas were repatriated in the early 1990's. However, vigilance must continue.