Varanus indicus (Daudin, 1802)
Family: Varanidae Mangrove Monitor Status: Indigenous? Description: The mangrove monitor is a very large dark lizard with small yellow spots and flecks. Adult males may reach up to 560 mm SVL and 2400 g. Adult females are much smaller measuring up to 440 mm SVL and weighing up to 1000 g (Wikramanayake and Dryden 1988). Hatchlings are black with larger yellow spots arranged in loose transverse rows. As animals age black pigment develops within the yellow spots and yellow pigment forms in the dark areas until, as adults, they appear uniformly speckled. Even as hatchlings, V. indicus is considerably larger than any other lizard in the area and is not likely to be confused with anything other species. Biology: The mangrove monitor occupies most habitats in the Mariana Islands but seems to be most common in limestone forest and in beach strand forest. It will eat a wide variety of vertebrate and invertebrates both living and scavenged. The author has observed this species eating cockroaches, mice, Carlia, and road killed pig. The voided stomach contents of a large individual captured on Pagan Island seemed to be composed entirely of cockroaches and hermit crabs. Based on the disparity in size between males and females, Wikramanayake and Dryden (1988) predicted that this species would engage in male to male combat and forced insemination. The observations made by McCoid and Hensley (1991) seem to support this. Distribution: Varanus indicus has been found to be composed of several morphologically similar species that collectively range from Northern Australia, Sulawesi, the Moluccas, Aru Island, Talaud, New Guinea, Timor, the Solomon Islands, and the Caroline, Marshal, and Mariana Islands. This species Varanus indicus, sensu sticto, occurs on most of the islands in the Marianas, though it has not been reported from Guguan, Uracas, and Maug (Vogt and Williams 2004). The monitor lizard has been present on Guam for at least 1500 years (Pregill and Steadman 2009). How long it has been on the islands and weather it made it to the Marianas unassisted by man is unknown. McCoid M.J. and R.A. Hensley. 1991. Mating and Combat in Varanus indicus. Herpetological Review 22. 16-17 Pregill G, and D. Steadman. 2009. The Prehistory and Biogeography of Terrestrial Vertebrates on Guam, Mariana Islands. Diversity and Distributions. 15 983-996 Wikramanayake, E. D., and G. L. Dryden. 1988, The reproductive ecology of Varanus indicus on Guam. Herpetologica 44(3): 338–344. |