Relative Abundance of Lizards and Marine Toads on Saipan, Mariana Islands

Abstract

Twelve species of lizards and the marine toad (Bufo marinus L.) were surveyed in six habitat types at three sites on the island of Saipan, Mariana Islands, using visual censuses, hand captures, and adhesive traps. Toads were rare on each of the study sites. Anolis carolinensis Cuvier was most common in disturbed forests. Four species of geckos, Gehyra mutilata (Wiegmann), G. oceanica (Lesson), Lepidodactylus lugubris (Dumeril & Bibron), and Perochirus ateles Dumeril, were most abundant in forests and abandoned buildings, and a fifth species, Hemidactylus frenatus Dumeril & Bibron, occurred most frequently on structures of all types and in open fields. The skink Carlia fusca Dumeril & Bibron was the most abundant diurnal lizard in all habitats. Emoia caeruleocauda de Vis occurred in all habitat types surveyed except open fields and was usually much less common than C. fusca. Emoia atrocostata (Lesson) was documented for the first time on Saipan, with a population found on a small offshore islet with scrubby strand vegetation. Lamprolepis smaragdina (Lesson) was relatively common at only one of three study sites, where it was seen primarily on large tree trunks. Varanus indicus (Daudin) displayed broad habitat use, but also was common in only one study area. At least five of these species are introductions, with C. fusca suspected of causing population reductions of other terrestrial skinks on the island.