Gila monster

Description

The Gila monster (Heloderma suspectum) is a species of venomous lizard native to the Southwestern United States and the northwestern Mexican state of Sonora. It is a heavy, typically slow-moving reptile, up to 60 cm (2.0 ft) long, and is the only venomous lizard native to the United States. Its venomous close relatives, the four beaded lizards (all former subspecies of Heloderma horridum) inhabit Mexico and Guatemala. The Gila monster is sluggish in nature, so it is not generally dangerous and very rarely poses a real threat to humans. Yet, its exaggeratedly fearsome reputation has led to it sometimes being killed, in spite of the species being protected by state law in Arizona. The Gila monster is found in the Southwestern United States and Mexico, a range including Sonora, Arizona, parts of California, Nevada, Utah, and New Mexico. No records have been given from Baja California. They inhabit scrubland, succulent desert, and oak woodland, seeking shelter in burrows, thickets, and under rocks in locations with a favorable microclimate and adequate humidity. Gila monsters depend on water resources, and might be observed in puddles of water after a summer rain. They avoid living in open areas, such as flats and open grasslands. Gila monsters spend 90% of their lifetime underground in burrows or rocky shelters. They are active in the morning during the dry season (spring and early summer). The lizards move to different shelters every 4-5 days up to the beginning of the summer season. By doing so, they optimize for a suitable microhabitat for survival. Later in the summer, they may be active on warm nights or after a thunderstorm. They maintain a surface body temperature of about 30 °C (86 °F). Close to 37 °C (99 °F), they are able to decrease their body temperature up to 2 °C (3.6 °F) by an activated, limited evaporation via the cloaca. One study investigating a population of Gila monsters in southwestern Utah noted the lizard's activity peaked from late April to mid June. The average distance traveled during their bouts of activity was 210 m, however some of the lizards would travel over one kilometer on occasion. During the Gila monster's active season of approximately 90 days, only ten of those days was the Gila monster active. Gila monsters are slow in sprinting ability, but they have relatively high endurance and maximal aerobic capacity (VO2 max) for a lizard. They are preyed upon by coyotes, badgers and raptors.