Record Details

Tershy, Bernie;Newton, Kelly M;Spatz, Dena R;Swinnerton, Kirsty J;Iverson, John B;Fisher, Robert N;Harlow, Peter S;Holmes, Nick D;Croll, Donald A
The biogeography of the threatened insular iguanas and opportunities for invasive vertebrate management
Iguanas: Biology, Systematics, and Conservation
Book Section
John B Iverson, Tandora D Grant, Charles R Knapp and Stesha A Pasachnik
Monograph 6
Herpetological Conservation and Biology
Amblyrhynchus cristatus mertensi;Amblyrhynchus cristatus nanus;Brachylophus bulabula;Brachylophus fasciatus;Brachylophus vitiensis;Conolophus marthae;Ctenosaura bakeri;Ctenosaura melanosterna;Ctenosaura oedirhina;Cyclura carinata;Cyclura carinata carinata;Cyclura collei;Cyclura cychlura cychlura;Cyclura cychlura figginsi;Cyclura cychlura inornata;Cyclura lewisi;Cyclura nubila caymanensis;Cyclura pinguis;Cyclura ricordii;Cyclura rileyi cristata;Cyclura rileyi nuchalis;Cyclura rileyi rileyi;Cyclura stejnegeri;Iguana delicatissima;Iguana iguana
Iguanas are a particularly threatened group of reptiles, with 61% of species at risk of extinction. Primary threats to iguanas include habitat loss, direct and indirect impacts by invasive vertebrates, overexploitation, and human disturbance. As conspicuous, charismatic vertebrates, iguanas also represent excellent flagships for biodiversity conservation. To assist planning for invasive vertebrate management and thus benefit threatened iguana recovery, we identified all islands with known extant or extirpated populations of Critically Endangered and Endangered insular iguana taxa as recognized by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. For each island, we determined total area, sovereignty, the presence of invasive alien vertebrates, and human population. For the 23 taxa of threatened insular iguanas we identified 230 populations, of which iguanas were extant on 185 islands and extirpated from 45 islands. Twenty-one iguana taxa (91% of all threatened insular iguana taxa) occurred on at least one island with invasive vertebrates present; 16 taxa had 100% of their population(s) on islands with invasive vertebrates present. Rodents, cats, ungulates, and dogs were the most common invasive vertebrates. We discuss biosecurity, eradication, and control of invasive vertebrates to benefit iguana recovery: (1) on islands already free of invasive vertebrates; (2) on islands with high iguana endemicity; and (3) for species and subspecies with small total populations occurring across multiple small islands. Our analyses provide an important first step toward understanding how invasive vertebrate management can be planned effectively to benefit threatened insular iguanas.