October 2021

Desert Tortoises

Ask most anybody to rattle off ten creatures that come to mind when you think of Arizona, and the likes of rattlesnakes, gila monsters, tarantulas, buzzards, javelina, bobcat, black widow and fiddle-back spiders, and maybe even centipedes and millipedes may make the list. But one of Arizona’s most long-term residents probably will not. In part, this may be due to the fact that though this creature can live to 75, even a 100 years, it is seldom seen. My wife and I moved to Arizona in 2004, but would not encounter our first javelina till 2016. And it was just this past week that we saw our first wild desert tortoise. That’s a long time to wait to see a native, but it was worth it. And the really neat thing was that we got a really good look at it, as we finally found a wild critter that moved at about the same speed as our own 78 year frames.

Anyhow, this wonderful encounter prompted me to learn more about these elusive creatures, and some of that I’ll pass on to you. Once fairly plentiful here, desert tortoises are now endangered, victims of the usual “roque’s list” of habitat loss, construction, roads, drought, introduced diseases, and the fact they reproduce slowly and have small clutches (4 to 8 eggs) and very high predation and mortality among the little guys. Turtle eggs are a favorite snack of gila monsters, badgers, kit foxes and coyotes. Once hatched, and slowly moving about, these same predators (plus a horde of others from bobcats to golden eagles) seek out the hatchlings.

Though only one or two of the clutch may survive, they are wonderfully adapted to their harsh environment.  Tortoises are vegetarian, enjoying grasses, sledges, tender pads and fruits of various cactuses, and flowers. Water, of course, is in short supply, but the tortoises are able to get most of what they need just from the plants they eat, and are able to store the water in their bodies, able to survive up to a year without imbibing open water. They can also tolerate very high levels of urea in their bodies, this conserving water that would otherwise be lost in urination. However, if they feel threatened, as when picked up by a predator (or human), a natural defense mechanism is to pee on the threat, usually occasioning its release. However, this escape ploy comes at a high price. Unless the tortoise can quickly rehydrate, to replace the water it lost, it is may succumb to dehydration.

Desert tortoises are the largest terrestrial turtles in the United States. They’ll reach adult lengths of up to 15 inches, and as many pounds. Hatchlings start off about 2 inches. Adults reach sexual maturity between 12 and 15 years. During the mating season, spring through summer, males are very aggressive towards each other, and in their sparring may overturn their opponent. So size and weight counts. Overturned, tortoises are in serious trouble, and unless they can right themselves will suffocate, or succumb to heat, cold, or predation.

As far as preferred home range, look for desert tortoises in creosote bush scrub habitats between 1,000 and 3,500 feet in elevation.  They are digger/burrowers and will descend to a depth that offers them comfort between extremes of hot and cold.  They’ll spend up to 98% of their lives underground (another reason they are seldom seen), hibernating in the winter, and also in “estivation” (a summer torpor) during times of extreme heat. During these “down” times, their heart rates, respiration, and all critical bodily functions slow down. Desert tortoises are most active in the spring, and after rains, so out and about during monsoons, where other critters might be seeking shelter.

Because they move slowly, tortoises are very vulnerable crossing highways. They also are subject to the 101 hazards of the harsh environments they inhabit. The Az. Dept. of Game & Fish has partnered withy the Az. Desert Museum in a tortoise adoptive program, where injured or needing special care tortoises are farmed out to caring private citizens deemed able to care for the creatures. The tortoises remain property of the state, but the civilian “custodians” in affect have the tortoises on a permanent loan. Captive tortoises are not re-introduced back into the wild, as once domesticated they would not fare well in nature. They also can pick up diseases to which the wild population has no immunity.

Tortoises are especially susceptible to respiratory diseases. I too. Add to that the facts that I move slow, and sleep a lot, I wonder if I might not have a bit of tortoise DNA. I, however, am not available for adoption. However, should you be interested in possibly adopting a wild Arizona desert tortoise, a wealth of information is available to you at:

www.desertmuseum.org/program/tap.php

There is a limit of one desert tortoise per person.  We have a tortoise, and I can vouch that they make for a wonderful addition to the home of any senior.  They don’t bark. They don’t bite. You don’t have to walk them, and if you prefer to, you can keep up with them.

Anthony de la Torre
Sun City Grand resident