Wondrous Wildlife
Monsters Sighted in Jalisco!
By Vern and Lori Gieger

     Gila monsters, that is. This elusive lizard spends the majority of its life underground; in the summer to avoid the heat, during the winter months, the Gila hibernates. Most of their above ground activity occurs for three months in the spring, when mating occurs, and when their source of food is most abundant. They are diurnal with activity occurring mainly in the morning.
     While the Gila is a non-aggressive lizard. It will however, defend itself if approached too closely. In this case, it will face its opponent with its mouth opened wide, hissing boisterously. If the Gila feels further threatened it will jump at the aggressor and bite. It was once believed that if a Gila monster bites, it will not let go until sundown or until it thunders. Although, this is false, Gilas do have a very powerful bite and are capable of hanging on tenaciously.
     Another long-held belief has been that the breath of a Gila monster is nauseating and poisonous. Nauseating yes, poisonous no. Considering their diet, it is no wonder they have serious halitosis! Their diet consists of carrion, (rotting flesh) various insects and small reptiles and rodents.
     The Gila is the source of many superstitions, the subject of legends. Even the real facts about this misunderstood creature are nothing short of amazing. Gila Monsters are one of only two species of venomous lizards. There are two species of Gilas: the reticulated, and the banded. While their bite is extremely painful, there are no reliable accounts of human deaths from Gila monster bites.
Gila monsters are adapted to eating large meals infrequently. In fact, an adult male Gila can consume its entire yearly energy budget in three or four meals! Wow! Talk about a diet plan! However, their food requirements are reduced by a low metabolic rate, as well as the relatively cool body temperatures they maintain. Gilas have specially adapted tails that allow them to store fat away for future needs. This allows them to consume most of their food during the limited spring activity period. (Well, I don’t know what’s so special about the tail; some of us have specially adapted thighs, which allows us to store fat. Problem is, it never seems to get used.)
     Immediately after eating, large quantities of a hormone-like molecule, called exendin-4 circulates in the Gila’s blood. With this unique mechanism of metabolic control, the act of eating primes the organism to receive the incoming nutrients.
On an interesting note, Exendin-4 is currently being investigated as a promising new drug to treat Type-2 diabetes. This peptide stimulates the secretion of insulin in the presence of elevated blood glucose levels. It also has the effect of slowing gastric emptying. Clinical studies have recently begun with a synthetic version of this protein.
     Humans tend to be the Gila Monster’s primary predator. This threat is primarily in the form of habitat destruction and over-collection. Danger lurks in other places as well; other reptiles eat the young Gilas. The adults are a food source for hawks and owls, particularly the Harris hawk, and the Great Horned owl, not to mention coyotes will not pass up the opportunity to dine on Gila. So, perhaps it’s a good thing that they spend the majority of their life underground!