Desert Dwellers - Biodiversity for a Livable Climate

Featured Creature: Yucca

What plant can also be used as a soap,
but without a certain insect, simply could not cope?

Yucca!

On a dreary, gray day at school, as I hurried from one academic building to another, I spotted a patch of spiky green shrubs, sticking out like a sore thumb. These plants gave me pause because though they were a familiar sight, I had last seen them in the high desert of Mancos, Colorado, a very different setting than my New England college campus, some 3,000 miles away. How did they get here? I wondered, and how are they thriving in an environment so different from the one I had last seen them in?

There are about 30 species of yucca, most of which are native to North and Central America. The yucca that I recognized on my campus walk was soapweed yucca, also known as great plains yucca. Soapweed yucca is a shrub with narrow leaves, almost knife-like in their sharpness, which can grow up to 3 feet tall. Soapweed yucca grows in the dry, rocky soils of short grass prairies and desert grasslands and thrives in more arid biomes. Still, it can be found across the United States; the yucca’s thick, rhizomatous roots (horizontal underground stems that send out both shoots and roots) allow the plant to thrive in many environments with different soils, including sand. It is a hardy plant, and can tolerate cold and moderate wetness, hence its ability to survive on my college campus in the Northeastern United States.

The shrub received its name, soapweed, due to the saponin contained in its roots. Saponin is a naturally occurring substance in plants that foams upon contact with water, creating a natural soap, which is something that I wish I had known as I camped feet away from the yucca in Colorado. In addition to its cleansing properties, the saponin has a strong bitter taste, and is used by plants, such as the yucca, as a deterrent against hungry insects and animals alike. For humans however, these characteristics make it an attractive partner. These saponin can be turned into sudsy cleansing soap. This process has been used by indigenous peoples for hundreds of years, and is modeled in the video below.

The flower and root of the yucca plant have been used as a nutritional, and tasty snack for centuries. As we learned earlier, the roots and flowers of yucca contain saponin, which, while offering medicinal and hygiene benefits, can be toxic or harmful if not properly prepared for consumption. When consumed, the saponin has a bitter taste, and can cause a burning sensation in the throat. However, if properly prepared, the yucca flower and root can be used in a variety of different recipes. The following video shows the proper way to prepare, and eat, yucca flowers.

In addition to eating the flowers of the yucca plant, the root holds incredible nutritional and medicinal benefit. Roots were used in a salve for sores and rubbed on the body to treat skin diseases. The sword shaped leaves of the yucca plant could also be split into long strips to be weaved into useful cords. Due to the strong fibers contained in the leaves, yucca could be stripped into thread to fashion baskets, fishing nets, and clothing.

The Yucca Moth

During the spring months, from the center of mature soapweed yucca blooms a beautiful stalk of cream colored flowers. At the same time as the yucca flower blooms, an insect called the yucca moth emerges from its cocoon. The yucca moth is small, and white in color, closely resembling a petal of the yucca flower, which allows the insect to blend in with the blossoms. There is a powerful symbiotic relationship between the yucca plant, and the yucca moth, meaning that two organisms have a long term, mutually beneficial biological relationship.

Yucca moths in flowers
(WikiCommons by Judy Gallager)

After breaking out of their cocoons, the male and female yucca moths find their way to the blossoms of the yucca flower, where they mate. The female yucca moth then gathers pollen from the yucca, flying to different plants which ensures the cross pollination of the plant. She shapes the pollen into a large lump, which she holds underneath her chin as she travels, searching for the proper flower to lay her eggs. This ball of pollen can reach up to three times the size of her head! Once located, she lays her eggs in the ovary of the yucca’s flower. She then deposits her collection of pollen onto the stigma of the flower, pollinating the yucca, which will now produce fruit and seeds for her larvae to feed off of. The larvae mature before they can
consume all of the yucca’s viable seeds, allowing
the yucca to continue to reproduce.

Flowering yucca
(pixabay by Thanasis Papazacharias)

Leaving her larvae, the eggs grow for a few weeks on their own. Once they reach the right size, the larvae drops from the yucca flowers to the ground, where it burrows underground and forms its cocoon. The lifespan of a yucca moth is only about a year, and the majority of that time is spent in the pupal, or cocoon stage, under the earth. Once an adult moth has mated, it marks the end of their brief life as adult moths. Once underground, the insect will remain in this cocoon in a dormant state until next spring, when the yucca flower begins to blossom, and the cycle continues.

The yucca moth is the primary pollinator of yucca plants, and its larvae depend on yucca seeds as a key food source. While the relationship is highly specialized, some yucca species can self-pollinate to a limited extent, and other insects, such as bees, may occasionally contribute to pollination. Without one, the other simply would certainly struggle to survive as they do today. Although yucca moths are native to the southwest areas of North America, as yuccas have expanded across the country, some species of yucca moths have also spread, although their distribution remains closely tied to the presence of their specific yucca host plants.

Perhaps the soapweed yucca that I stumbled across in New England autumn already had cocoons of yucca moths, lying hidden and dormant beneath my feet.

Helena Venzke-Kondo is a student at Smith College pursuing psychology, education, and environmental studies. She is particularly interested in conversation psychology and the reciprocal relationship between people and nature. Helena is passionate about understanding how communities are impacted by climate change and what motivates people towards environmental action. In her free time, she loves to crochet, garden, drink tea, and tend to her houseplants.

Sources and Further Reading:

Featured Creature: Cheatgrass

What plant plays an important role in the grasslands of its native hemisphere, but alters soil moisture and fire regimes when introduced in North America?

Cheatgrass (Bromus tectorum)!

A cheatgrass seed had needled its way into my skin again. I thought that I had freed myself of the cheatgrass when I came back east, to the land of ample water and broad leaves, and threw all of my camping gear into a dark corner of my bedroom. This was not so – it was hiding out in my sock drawer. When I pulled up my socks, I dragged the pointed tips of the cheatgrass seeds up my ankles, and I was once again somewhere out west, nursing the delicate white surface wounds that they left. I was, for the first time, not grateful for the tight warmth-trapping weave of my wool hiking socks – it is highly adept at locking the lance-like grass seed into a comfortable chamber from which it can prod at my ankles. The cheatgrass survived the washer and the dryer and my prying fingernails, survived my desperate attempts to wrench it out of my socks and into the campfire. Cheatgrass burns fantastically well– it’ll ignite from marshmallow-toasting-distance and beyond.

My cheatgrass came with me from Wyoming months ago. Out there, it rolled for miles across the sagebrush steppe, slowly but surely creeping into every space between every shrub. The site where I gathered the seeds into my socks smelled more of earth than sagebrush, which was unusual for the basins where I’d been working. My boss Rachel and I hopped down out of our work truck and took in our site: some sagebrush, sure, but only a few dashes of it scattered between rolling hills of crisp, flame-red cheatgrass. The site was nearly silent; I found myself missing the usual distant whirrr of farm machinery and the cacophonous cry of a startled sage grouse. We were instead accompanied by the whistling of wind and the knowledge that we would be blowing dust into our handkerchiefs for a few days.

The Sagebrush Steppe near Big Jacks Creek Wilderness, Idaho, has been almost entirely taken over by cheatgrass.

“Downy Brome”

Some call cheatgrass “downy brome”, which is a perfect term for it in the early spring when it hasn’t grown into its wretchedness. In early spring, when its long awns have not yet grown stiff and sharp, it is a soft and elegant plant. Its leaves fall in a gentle cascade from the long stem. The downy brome rolls over hillsides and whispers to its sisters in the breeze; as they dry in late summer, the wind knocks the heads of their seeds against one another, and they are scattered to the ground to start their cycle anew. When the cool season rains end and they’ve sucked up all the water they can from the parched earth, their chloroplasts finally falter, and the grass turns a faint purple-red from the awn-tip up. In spring, the dusty green tones of the sagebrush and the brightly-colored grass dapple the landscape. By summer, the sagebrush is nearly overtaken by an orange-brown, foreshadowing the fire which cheatgrass so often fuels. The grass sticks its seeds through your shoes and between your toes and into your socks and the hems of your pants. It doesn’t matter if you stop to pull them out– you will have just as many jabbing and nudging away at you after you walk another ten feet through their swaying abundance. It is useless to shake them out, too. You must pull them, piece by piece, out of your hair and your tent and your boots, and cast them to the ground. This is just what they wish for– you are seeding them for next year.

A rugged invader

Humans introduced cheatgrass to the Northeastern United States by accident sometime around 1860. You can find it in many places around New England, but in the presence of such an overwhelming amount of water, it often fails to compete with its fellow grasses and is relegated to cracks in sidewalks and highway islands full of compacted, inhospitable soil. Cheatgrass seems lost on this coast; few in the East know what it is or why it’s here. It is a plant surviving as plants do, regardless of the “invasive” status we’ve thrust upon it. In the West, however, its success is something wicked and wonderful.

Any water from the winter’s snowmelt or early spring rains gets sucked up by the eager roots of the cheatgrass, leaving little for the still-sprouting native grasses, forbes, and shrubs, even as their taproots probe deep into the earth. Ecologists curse the plant for its brutal efficiency in driving out those native to the arid steppe; birders lament the loss of woody habitat for their feathered favorites; ranchers sigh at the sight of yet another dry, nutritionally-deficient plant that even their toughest cow is loath to graze. And there is, of course, the fire. Cheatgrass dies and dries in the early summer, long before native grasses do, providing an early fuel source for the ever-lengthening fire season.

Cheatgrass seeds
Jose Hernandez, USDA (Public Domain via Wikicommons)

The seeds lie in wait in the earth, and in the spring, they unfurl their new leafy heads and emerge from between blackened sagebrush branches. In the grass’s native range in Europe and Southwestern Asia, the plant is no worse or better than any other; it just is. Moths and butterflies lay their eggs along its edges. Ungulates nibble it slowly as their eyes each search opposite directions for the next snack.

Nearly all of the existing research on the plant explores its role far from home, in the United States. It is grass, and it would be hard to imagine that here on the other side of the world, some field tech is cursing its very existence. You’d never know from looking at the cheatgrass that ranchers and federal scientists alike have spent years dousing their own lands in herbicides with the hope of its extirpation. We humans have of course played our role in keeping the cheatgrass strong even as we try to drive it out, since cheatgrass, like many invasives, is far better at taking over already-disturbed soils where the native plant communities and biological soil crusts have been weakened. As extreme wildfires, agricultural use, overgrazing, and the general ravages of climate change continue to impact larger and larger regions, so too does the invasive capacity of the cheatgrass.

I wore a different pair of socks hiking that day for fear of bringing more cheatgrass to Connecticut. It was silly, though; the cheatgrass already knows this land well.

Jasmine

Jasmine Gormley is an environmental scientist, writer, and advocate from New Hampshire. She holds a BS in Environmental Studies from Yale, where she conducted research in plant community ecology and land management. She aims to obtain a degree in environmental law. As a first-generation college student, she is passionate about equity in educational and environmental access, and believes that environmental justice and biodiversity conservation are often one and the same. In her spare time, you can find her rock climbing, foraging, and going for cold water swims.

Sources and Further Reading:

Featured Creature: Gila Monster

What creature has a venomous bite and is uniquely adapted to survive harsh desert terrain?

The Gila monster!

Image by Josh Olander CC BY 4.0 via Wikimedia Commons

Be not afraid! The Gila monster is not a monster at all, but rather a unique lizard with special adaptations. This reptile is native to North America’s Southwest region including Arizona, Utah, Nevada, and Northwest Mexico. It is so named because of its discovery by herpetologist and paleontologist, Edward Drinkerin, in the Gila River basin.

The Gila monster is a lizard of substantial size, weighing about 1.5 – 3 pounds and clocking in at over 1 foot long. Males are characterized by their larger heads and tapering tails, while females have smaller heads and thicker tails. Its black and orange skin is easily identifiable and comes in two patterns – banded and reticulated. The banded and reticulated Gila monsters are recognized as two distinct subspecies.

Reticulate Gila Monster (Image by Jeff Servoss, Public domain via Wikimedia Commons)

Desert Dweller

This creature is suited for hot, arid environments like the Sonoran and Mojave deserts, where tough skin is needed for a tough landscape. The Gila monster’s beaded skin is created by osteoderms, small bumps of bone beneath its thick skin, that armor the lizard against predators and the harsh terrain.

When desert temperatures soar over 105 degrees Fahrenheit (or 40.5 degrees C), even the Gila monster needs shelter from the sun. Like all reptiles, the Gila monster is cold-blooded and cannot regulate its body temperature on its own. So when it gets too hot, the monster needs to retreat to a shady place to cool down – a burrow. Gila monsters are equipped with long claws to dig burrows in the sand. These lizards spend 95% of their time underground to avoid scorching heat and will often sleep during the day to hunt at night.

Diverse Diet

Gila monsters prey on insects, birds, small mammals, and frogs. They especially have a preference for eggs and will unearth turtle eggs or raid bird nests. Gila monsters use their forked tongue to process scents and track prey. These carnivorous lizards will climb cacti to devour the eggs of a bird’s nest or even stalk a mouse to its burrow in search of young offspring. In harsh environments, sustenance is difficult to come by so when it gets the chance, the Gila monster can eat 35% of its weight in food. Any unused calories are stored as fat in its tail.

When hunting live prey, it subdues its victim by secreting venom through grooves in its teeth. Venom glands are based in the lower jaw and, unlike snakes that strike and inject venom in seconds, Gila monsters must bite and hold or gnaw their prey to release their venom. They have a very strong bite and can clamp on for over 10 minutes.

While the bite of a Gila monster is painful, it is not deadly to humans. Gila monster venom is most similar to that of the Western diamondback rattlesnake, but the amount of venom released into the wound is much lower. Symptoms from a Gila monster bite include extreme burning pain, dizziness, vomiting, fainting and low blood pressure. Because of their solitary and secretive nature, Gila monster bites are very rare and most cases are from improper handling of these creatures.

Hatchlings

When it comes time to reproduce, female Gila monsters lay 3-20 eggs in their burrows during July. The incubation period for Gila monster eggs can be as long as a human pregnancy, about 9 months. This is unusual as most reptiles incubate their eggs for just 1-2 months. The reason for such a long incubation period is thought to be due to overwintering.

Overwintering is a survival method where hatchlings emerge from their eggs, but not their nest. Gila monster hatchlings stay in their burrow, waiting for weeks to months, for temperatures to rise and food sources to increase. But how can they survive for months without food? Gila monsters are born with fatty tissue in their tails that permits them to forgo consumption. Additionally, they will eat the nutrient-dense yolk from their egg which provides substantial calories.

Baby monsters are just about 5 inches long and look like a miniature version of an adult. When conditions are right, they will leave their burrow to hunt for insects and begin their solitary life in their desert habitat.

Photo by Michael Wifall from Tucson, USA, CC BY-SA 2.0 via Wikimedia Commons

Cultural Significance

The Navajo revere the Gila monster as a strong and sacred figure. The Gila monster is often called the first medicine man and had healing and divining powers. Now, the Gila monster is Utah’s official state reptile and represents Utah’s connection to both its Indigenous culture and wildlife.

Despite the recognition, Gila monsters are listed as ‘Near Threatened’ by the International Union for Conservation of Nature (IUCN). There is an estimated population of several thousand left in the wild. Major threats include habitat loss from increased development and illegal poaching for the pet trade.

Venom of Value

The Gila monster’s venom has been a point of interest in the scientific community. While there is no antivenom for bites, there is hope to utilize its venom for medical use. Scientists discovered that a specific hormone within the Gila monster’s venom can alter the way cells process sugar – a potential cure for diabetes. By isolating this hormone, researchers were able to replicate it synthetically. After years of testing, a new drug to help with Type 2 diabetes was released in 2005 under the name Byetta – all thanks to the existence of the Gila monster.

Even the most unlikely organisms can have a great impact on humanity, which is one of the reasons why it is so important to preserve biodiversity. “Monsters”, allies, or wonders – you be the judge.

Signing off for now,
Joely

Joely Hart is a wildlife enthusiast writing to inspire curiosity about Earth’s creatures. She holds a Bachelor’s degree in creative writing from the University of Central Florida and has a special interest in obscure, lesser-known species.

Sources and Further Reading:
https://www.aboutanimals.com/reptile/gila-monster/
https://blog.kachinahouse.com/the-lizard-in-native-american-culture/
https://www.livescience.com/65093-gila-monsters-photos.html
https://lazoo.org/explore-your-zoo/our-animals/reptiles/gila-monster/
https://www.nhm.ac.uk/discover/the-monster-whose-bite-saves-lives.html
https://kids.frontiersin.org/articles/10.3389/frym.2019.00017

Featured Creature: Prairie Dog

Have you ever heard of a squirrel that barks?

Let me introduce you to the Prairie Dog.

Sometimes, when walking alone in the high grasslands of the Western United States, you may feel as if you are being watched.

My first encounter with prairie dogs in the wild occurred as I stood in an empty prairie just outside of Badlands National Park in South Dakota. As I meandered along, minding my own business, dozens of furry creatures with beady little eyes appeared, propped themselves up on their hind legs, and began to follow my every step. Prairie dogs are adorable, it is true, but when you see a dozen spread out, standing upright, watching you intently, it can be a bit disconcerting.

They were, however, no threat, and weren’t eyeballing me just to judge me. A prairie dog standing on his hind legs – “periscoping” as it is known – is simply keeping watch for predators. And their distinctive bark? It may sound like “yip,” but it is actually a sophisticated language developed over thousands of years that is still not fully understood by scientists.

Prairie dog barks convey everything about a predator’s size, speed, and location. According to a study at the University of Northern Arizona led by Con Slobodchikoff, Ph.D (see video linked below) pitch, speed, and timbre were all altered in a consistent manner corresponding to the species of predator and the characteristics of each. Certain “yips” could even be interpreted to represent nouns (the threat is “human”), verbs (the “human” is moving toward us), and adjectives (the “human” is wearing an ugly yellow shirt). So now that I think about it, I guess they were judging me, and I am not sure how I feel about that. But still, those are some impressive squirrels.

Wait, did you say squirrels?

Yes.

Squirrels. From the Sciuridae family. Prairie dogs are marmots (or ground squirrels) that bark like a dog, prompting Lewis and Clark to label them “barking squirrels,” which may lack points for creativity but is at least more accurate than calling them “dogs.” Prairie dogs, in fact, have no connection to dogs whatsoever.

Amaury Laporte (CC BY 2.0 via Wikimedia Commons)

There are five major species of prairie dog, who all live in North America at elevations between 2,000 and 10,000 feet. The Black-Tailed prairie dog covers the largest territory, filling an extensive region from Montana to Texas. Gunnison’s prairie dogs occupy the southwest near the Four Corners region. White-Tailed prairie dogs reside in Wyoming, Utah, and Colorado. Mexican and Utah prairie dogs belong to Mexico and Utah, respectively, and both are considered endangered.

As you may have observed, prairie dogs live in areas prone to harsh extremes of weather. To protect themselves, they dig extensive burrow networks with multiple entrances, designed to create ventilation, route flood water into empty chambers deep underground, and keep watch for predators. Their burrows connect underground, organized into sections called “coteries,” each of which contains a single-family unit responsible for the maintenance and protection of their area. Multiple coteries become “towns” of startling size and complexity. According to the National Park Service, the largest prairie dog town on record covered 25,000 square miles, bigger than the state of West Virginia!

That IS an impressive squirrel.

Indeed.

Over the years, however, the prairie dog’s range has shrunk, scientists estimate, by as much as 99%, largely because of agriculture. Farmers and ranchers tend to regard prairie dogs as a nuisance, as they sometimes eat crops (they are mostly herbivores) and their holes create a hazard for livestock. They will bulldoze their towns or conduct contest kills to remove them, which has had devastating impacts.

Experts consider prairie dogs to be a keystone species. Their loss affects hundreds of other species who rely on them for food or use their burrows for shelter. They are instrumental in recharging groundwater, regulating soil erosion, and maintaining the soil’s level of production. Prairie dog decline, in fact, eventually leads to desertification of grassland environments.

So, an impressive AND important squirrel?

Yes, and the restoration of prairie dog habitats could be a crucial step in mitigating the effects of climate change.

If you’ve caught prairie dog fever, dive deeper into the resources below. And to learn more about Prairie Dog language, check out this fascinating video:

Hoping one day to converse with my personal prairie dog army,

Mike

Mike Conway is a part-time freelance writer who lives with his wife, kids, and dog Smudge (pictured) in Northern Virginia.

Sources:
https://animals.net/prairie-dog/
Prairie dog – Wikipedia
https://www.humanesociety.org/resources/what-do-about-prairie-dogs
Prairie Dog Decline Reduces the Supply of Ecosystem Services and Leads to Desertification of Semiarid Grasslands | PLOS ONE
Prairie Dogs | National Geographic
Prairie Dogs: Pipsqueaks of the Prairie (U.S. National Park Service) (nps.gov)

Creature: Desert Dwellers