Protecting Land Iguanas in The Galapagos Islands - On the Island of Santa Cruz an incubation and raising program is maintained for the eventual repatriation of land iguanas. (Conolophus subcristatus.)
In 1975 it was noticed that some iguana populations were dwindling and threatened with extinction by the presence of introduced animals. The last individuals of Carthago-bay (20) on Isabela Island and Conway bay on Santa Cruz Island, were removed from their natural dwellings and kept in custody at the GNP and CHDF s´ facilities to reproduce and repopulate these habitats long-term.
Parallel, systematic control and dog and cat eradication-programs have been implemented in those areas where land-iguanas roam and nest. Between 1981 and 1982, all dogs and cats where eliminated from Conway and Carthago bay. Repatriation commenced in 1982. Until 1995, 390 juvenile land iguanas have been repatriated to Carthago bay and 183 to Baltra Island. Additionally, field work has been carried out at “Venecia “(Santa Cruz) where reproduction efforts in semi-captivity were implemented. Until 1995, 264 iguanas have been transferred this way.
Land iguanas in the wild. Land iguana populations have been monitored during the last 30 years, especially in Conway and Carthago bay where they were decimated by wild feral dogs and cats.
The populations of land iguanas on Santa Fe Island, North Seymour and on the volcanoes north of Isabela Island are monitored to assess their distribution, abundance and possible threats. Until now we assume their populations to be stable.
Before the II WW, Baltra Island had a great land-iguana population. This was possibly a distinct race. In 1932 and 1933 a group of scientist transferred 70 iguanas to North Seymour Island (where iguanas never existed before) in order to improve their survival conditions as on Baltra island their was great food-scarcity causing mal-nutrition in the animals. The vegetation on Seymour Island, on the contrary, was abundant.
During the war, Baltra was lend to the USA-military. Habitat destruction, alteration and introduction of feral animals like dogs and cats brought the iguanas to extinction on this Island.
On the other hand, the reproduction of the land-iguanas on north Seymour Island had not been successful. It is obvious that the ecological conditions for the survival of this race of land iguanas, are only present on Baltra Island.
The raising of land-iguanas on North Seymour Island started in 1980 with the transference of several adult individuals to the facilities of the land-iguana raising-center on Santa Cruz. The objective was to reestablish the land iguana population on the original Island of Baltra.
During several years field trips were made to the different Islands to determine the population densities. It is known that there are 416 individuals on Darwin volcano, and that 128 individuals were marked on Wolf volcano (including the pink population of the summit). Population estimates indicate the presence of 785 iguanas at Carthago bay (Isabela Island), 214 on Conway bay (Santa Cruz Island) and 283 on Baltra.
Land iguana studies on Santa Fe (Conolophus pallidus) demonstrate that the population is in good health. This endemic species counts with 1210 individuals. The healthy population status is maintained on Santa Fe likely due to the presence of the native predator, the Galapagos Hawk (Buteo galapagoensis).
The reproduction, nesting & hatchling of newborn iguanas are viable. The limiting factor for juvenile recruitment is the presence of the Galapagos Hawk and feral cats. Newborns are more vulnerable when they emerge from nests.