Page 5 - Fort Irwin High Desert Warrior, August 2022

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High Desert Warrior 5 August 2022
News
Desert Tortoise: A most elusive desert inhabitant
The desert tortoise is one of most elu- sive inhabitants of the desert, spending up to 95% of its life underground.
Desert tortoises live in a variety of habitats — from sandy flats to rocky foothills, including alluvial fans, washes and canyons where suitable soils for den construction might be found.
Tortoises have lived in the area that is now the Mojave Desert for millions of years, even before it was a desert.
As recently as the mid-1900s, people commonly encountered these familiar, gentle creatures. Today, however, they are rarely seen and in some places they have disappeared entirely. The Mojave Desert tortoise was listed as threatened on April 2, 1990.
The vast majority of threats to the desert tortoise or its habitat are associated with human land use. The most apparent threats to the desert tortoise are those that result in mortality and permanent habitat loss across large areas. These include urbanization and large-scale renewable energy projects, as well as those that fragment and degrade habitats, such as proliferation of roads and highways, off-road vehicle activity, habitat invasion by non-native invasive plant spe- cies, wildfire, and subsidized predators (especially common ravens). These threats interact in complex and synergistic ways to impact tortoise populations.
The desert tortoise requires 13 to 20 years to reach sexual maturity, has low reproductive rates during a long period of reproductive potential, and individ- ual tortoises experience relatively high mortality early in life. These factors make recovery of the species difficult. Even moderate downward fluctuations in adult survival rates can result in rapid population declines. Thus, high survivorship of adult desert tortoises is critical to the species’ persistence, and the slow growth rate of populations can leave them susceptible to extirpation events in areas where adult survivorship has been reduced.
Another factor integral to desert tor- toise recovery is maintaining the genetic variability of the species and sufficient eco- logical heterogeneity within and among populations to allow tortoises to adapt to changes in the environment over time.
Because desert tortoises occupy large home ranges, the long-term persistence of extensive, un-fragmented habitats is essential for the survival of the species. The loss or degradation of these habitats to urbanization, habitat conversion from frequent wildfire, or other landscape mod- ifying activities place the desert tortoise at increased risk of extinction.
Desert tortoises love eating some of
the native plants and forbs that grow here, and recent rains at NTC/Fort Irwin has energized plant growth. As a treat for the captive tortoises at DPW, wildlife biologist David Davis picked two bouquets.
We should leave wildlife wild and leave tortoises alone too. Only if they are in the middle of the road and in harm’s way, are we allowed to move them.
For more on how and when to move a desert tortoise, watch this video https://www.nps.gov/jotr/learn/na-ture/ tortoise.htm.
We can learn to live safely with rattlesnakes
There have recently been a lot of re- ports about sidewinder rattlesnakes, and a trained DPW biologist can safely remove and relocate snakes such.
Sidewinder rattlesnakes are venomous pit vipers, but they are shy and mostly nocturnal, resulting in relatively few bites to humans. They also do not appear to be aggressive.
The snakes feed almost exclusively on small rodents -- mice and kangaroo rats, and lizards. At night, they roam relatively long distances, smelling the air and substrate for prey.
One adaptation helping sidewinders
survive in their desert habitat is rough
scales. These scales allow them to move in
an S-motion across the hot sand without
burning themselves. In fact, they can
travel at a speed of up to 18 mph! A roadrunner can run up to 20 mph, if necessary.
Snakes have a life-saving physiological characteristic known as venom metering. Venom is physiologically costly to produce, so they do not waste it, unless provoked or killing prey. Even young snakes monitor how much venom they will inject. Rodents, lizards and small birds are on their menu —
can be a building, a bush or a vehicle. Oftentimes, a snake that is resting during the daytime will move as the temperature drops.
• When sitting down, watch where you put your hands and feet.
• Snakes may wait until it is dark to forage for food.
• Snakes usually only attack in self- defense. So if you see a snake, watch from a safe distance.
On the one hand, snakes are the natu- ral predators of disease-ridden rodents. On the other hand, snakes are also food for birds of prey — hawks, falcons, eagles and roadrunners.
In more than 30 years, only five people at Fort Irwin have been bitten by snakes. Four of these involved people trying to “grab” the
snake and were all bitten on their hands.
We can all learn to live safely with snakes, and appreciate
their important role in nature.
For more information or help relocating a snake, call 24-
Hour Wildlife at 619-288-8883 or the Fort Irwin Directorate of Public Works at 760-380-5909.
A sidewinder “horned” rattlesnake.
not humans.
There are proactive measures we can take to minimize
adverse encounters with snakes:
• Be alert and be aware that NTC/Fort Irwin is at the end
of the “world’s longest cul-de-sac” which ends in a desert wilderness.
• Be aware of temperature gradients. When it is hot (95 degrees or more), snakes will seek shade and shelter. This
For more information go to home.army.mil/irwin