Evergreens hunched against the wind . . . the haunting laugh of a canyon wren . . . a canopy of blue sky over the burning desert. This is wilderness a place that offers a superior kind of pleasure, where nature remains untarnished and undepleted . . .

Tuesday, August 31, 2010

Naturalist View September 2010

As summer wanes, I look forward to lizards and butterflies. Of course they have been active all summer but September is my “Bug month”. When you have bugs you have lizards.


Whiptail lizards
Among my favorite lizards are the Whiptails, a slender, shiny and colorful lizard that searches for ants and other insects found in the litter on the ground. While hunting it moves with a short jerky motion and turns over litter with its nose looking for prey. When you spot one you can be certain that it is a female. Why you ask? I am glad that you asked. No examination is necessary since all the known species of whiptail lizards reproduce by a process called parthenogenesis. The eggs produced by the female have a full set of chromosomes, so no male is needed to fertilize them and the offspring are perfect clones of the mother. Some ladies I know think that this is a really good idea.


It’s a Girl!

Desert Spiny Lizard
Of course we have all seen the most common lizard of Saddlebrooke the Desert Spiny Lizard. Almost every yard has its resident spiny. You can often see them running across the street looking for a mate, or a fight with a neighbor lizard. I have seen hundreds of them in the road during a monsoon shower lapping up the water for a rare drink.



Horned Lizard
Often called a “Horned or Horny Toad” this Lizard reminds us of the Dinosaurs of the past. This diurnal ground-dweller can be active at any time of the year but winter activity is usually restricted to unseasonably warm days. It seeks shelter from cold temperatures by burrowing into the soil, and occasionally squirts blood from its eyes when threatened or captured. This blood might have a foul taste designed to deter predators. Other defensive behaviors include inflating itself by gulping air and “poking” with the horns. These spiny “horns” protect the lizard from predators, such as snakes that would find it hard to swallow. The Horned Lizard feeds primarily on ants but it also takes beetles and other insects.


I am a Lizard! I am not a Toad!

Banded Gecko
You may come across our next lizard when turning over rocks or debris or more likely at night while it is hunting insects attracted by your porch light. The delightful Banded Gecko is a small (3" from snout to vent), creamy yellow lizard with reddish brown cross bands, spots, and reticulations on the body and tail. The scales are small and granular and the skin is soft and translucent.

Western Banded Gecko

Gila monster
With dozens of lizards in the Southern Arizona region, it is impossible for me to cover all the lizards you may encounter here in Saddlebrooke. So I will conclude with my very favorite the infamous Gila Monster (Heloderma suspectum)

A Tohono O’Odham myth
Indians and animals were invited to attend the first saguaro wine festival. Of course, party goers wore their best. Gila monster, not wanting to be dowdy like some lizards, gathered bright pebbles and tossed them over his back, making a durable and beautiful coat.

The Latin name, Heloderma suspectum, reflects the impression given by this animal: the Greek heloderma, studded skin; suspectum: suspected to be poisonous. In Mexico, both the Gila monster and the beaded lizard are called “escopiĆ³n” or “spitter,” because of the misconception that these lizards spit venom at their enemies.

Most people, when asked to name a venomous reptile, would think of a snake, and would probably not even realize that there are two species of venomous lizards that live in the Sonoran desert - the gila monster, Heloderma suspectum, and the Mexican beaded lizard, Heloderma horridum. Until 2009, they were thought to be the only venomous lizards in the world. Recent research has shown that the Komodo dragons also have venom. Until now the thought was that their prey died from bacterial infection from their bite. I was not aware of that when I was stalking them with my camera (and two guides) recently on Komodo Island in Indonesia.

Gila monster venom is a neurotoxin that causes respiratory failure in small mammals. So far there is no authenticated proof that anyone has died from their bite. A newspaper report that a man from the Phoenix area died from a Gila Monster bite in the late 1890’s prompted investigation that revealed that, yes the man had been bitten, and yes he had died but failed to mention that the events were twelve years apart.

These lizards have a tenacious bite in which they hold on to their prey. During this time they tend to gnaw, which seems to aid in the delivery of the venom. Unlike snakes they do not inject venom through fangs, but chew the venom (which is mixed with the saliva) into the wound.

Frightened by these oversized lizards, territorial settlers made up some gruesome tales, which gave the Gila monsters a nasty reputation. Every time one clamped its jaws onto a person and refused to let go, the lizard’s legend grew. They will open mouth and hiss when disturbed or threatened. A Gila monster will defend himself, but it’s not looking for a fight.

In 1959, a really bad movie, “The Giant Gila Monster” came out which did not help this poor lizards reputation. It has since become a cult classic. Well you probably saw it with your date at the Drive-In back in ’59.
Note: actually the lizard used for the movie is a Mexican Beaded Lizard


The Gila Monster is very selective about the people they bite. Statistics show that most bites occur to younger males that have been drinking, have Tattoos and only after they say “Here hold my beer and watch this!” Of the 40 or 50 Arizonans bitten by Gila monsters in the past few years, only a few had to spend the night in the hospital. The bites hurt, but no one dies.

Rule one: Don’t hassle a Gila monster and it won’t hassle you.

Rule two: Don’t put your hand where your eyes can’t see.

Many stories are told by Indian tribes of the Southwest about the magical powers of the Gila Monster.
When a Navajo storyteller tells the tale of the Gila Monster, his mind returns to the forgotten days when Gila Monster was the first medicine man. If the storyteller happens to be a medicine man, he may, at the outset of the tale, open up his pouch, full of sacred pollen, and sprinkle some around the four directions. When he does this, he is especially mindful of Gila Monster. For not only is this a medicine story particularly suited to Gila Monster's divining power, but it is also a "myth of armor," of covering the body with a protective shield, of which Gila Monster with his hard scales is considered the best and most exemplary veteran. He is the well-armored warrior of the Navajo. When abroad in the desert, crawling around his domain, Gila Monster's forefoot trembles as he walks. Navajos say that he is the original hand-trembler, which means that he can foretell the nature of mortal illness and protect against it.

Gila monsters are ectotherms. Like other lizards, they rely on their surroundings to maintain a preferred body temperature. The big lizards function at their optimal body temperatures in cool, underground burrows. They may remain underground for months at a time and survive on reservoirs of fat and water in their bodies. However they must eventually surface to eat, drink and reproduce.

One of the first things they do is search for food. Gila monsters are expert nest raiders. They don't just come across bird and rodent nests on a regular basis; they spend a lot of time roaming the desert searching for food. It can take days, weeks or a month to find a nest. That leaves them at risk for temperature extremes, either during the day when it can be too hot or at night when it’s far cooler than their preferred body temperature (approx 85°F)

Gila monsters solve this problem in some very clever ways. They minimize the time they spend on the desert’s surface by gorging on food when they find it. Some Gila monsters have been known to clean out a nest of juvenile rabbits in a single feeding.

They can eat up to 100 percent of their body weight at one time. Much of this food energy is stored as fat reserves in the lizard’s body cavity and tail. Gila monsters draw sparingly from these energy reserves when they retreat to underground burrows. They might stay in the burrows for months at a time during winter. They are also capable of storing large amounts of water. This portable water supply allows the lizards to roam far and wide without dehydration. But, since water is heavy, they will jettison their fluid burden when other sources are readily available in the wild. In the Sonoran Desert, Gila monsters have a peak of activity after the summer monsoons stimulate another spurt of breeding.

The Sonoran Desert’s “hot season” lasts from April through October. To minimize water loss, Gila monsters are most active at night when temperatures dip to 70 to 80 degrees F. At the onset of winter, they tend to locate their holdouts in south-facing rock outcrops. These areas offer protection from the season’s cold. They also provide warm basking sites when the lizards emerge in early spring. During the summer months, however, the lizards tend to retreat into far cooler earthen burrows. Among the most desirable are packrat middens. Once the lizard finds just the right kind of shelter they will use them over and over again.

Currently, Gila monsters are not officially listed as either a rare or endangered species. But their populations exist in highly localized pockets, many of which are experiencing a surge of human development. They are quite often found in swimming pools and ponds where they have gone in their quest for water. Unfortunately if they can’t get out they will tire and drown. Call me I know how to give mouth to mouth resuscitation.
 
Gila monster

Looking forward to hearing from you


About Me

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Saddlebrooke (Tucson), Arizona, United States
I am a retired school teacher from Monterey Bay Area in California. I now volunteer as naturalist at Arizona State Parks. I also work with a wildlife rehab center and I present natural history programs to the public.