Estado poblacional de las iguanas terrestres (Conolophus subcristatus, C. pallidus y C. marthae: Squamata, Iguanidae), Islas Galápagos.

Three species of land iguanas exist in Galápagos, all belonging to the same genus Conolophus. Of these, C. pallidus (Heller 1903) is endemic to Santa Fe Island; C. subcristatus (Gray 1831) occurs in 11 sites in four islands, whereas C. marthae (Gentile and Snell, 2009) inhabits the northern-western slopes of volcan Wolf (Isabela, island), above 500 m o.s.l. Census surveys indicated that four C. subcristatus populations were extinct, two were seriously impacted by wild dogs and cats. One of the extinct populations was restored and at present all reproduce in situ. Populations were investigated in order to assess adaptability and survivorship of reintroduced juveniles. Mark-recapture methods, simulation models, records of mortality and predation were used. Conolophus subcristatus occurs in 11 sites, in four islands, whereas C. pallidus and C. marthae are strictly endemic to the inhabited localities. These priliminary estimates suggest that C. subcristatus population might be as large as about 11435 individuals, whereas C. pallidus could reach about 5016 individuals. Much less has been estimated for C. marthae, whose population is most likely not exceeding 545 individuals. Population estimates are correlated with densities. Seven C. subcristatus populations and C. marthae show lack of juveniles, which are in turn found in C. pallidus. Generally, with the exception of Plaza Sur and Fernandina where female outnumber males, sex-ratio is biased toward males. Natural mortality seems to be minimal in all species, but C. subcristatus and C. marthae are predated by feral cats and black rats. Although this study is based on a large body of data, results are still to be considered preliminary. In addition, several spotted populations of C. subcristatus have not been evaluated, yet.